ESMO expert consensus statements (ECS) on the definition, diagnosis, and management of HER2-low breast cancer

Human epidermal growth factor receptor 2 (HER2)-low breast cancer has recently emerged as a targetable subset of breast tumors, based on the evidence from clinical trials of novel anti-HER2 antibody-drug conjugates. This evolution has raised several biological and clinical questions, warranting the establishment of consensus to optimally treat patients with HER2-low breast tumors. Between 2022 and 2023, the European Society for Medical Oncology (ESMO) held a virtual consensus-building process focused on HER2-low breast cancer. The consensus included a multidisciplinary panel of 32 leading experts in the management of breast cancer from nine different countries. The aim of the consensus was to develop statements on topics that are not covered in detail in the current ESMO Clinical Practice Guideline. The main topics identified for discussion were (i) biology of HER2-low breast cancer; (ii) pathologic diagnosis of HER2-low breast cancer; (iii) clinical management of HER2-low metastatic breast cancer; and (iv) clinical trial design for HER2-low breast cancer. The expert panel was divided into four working groups to address questions relating to one of the four topics outlined above. A review of the relevant scientific literature was conducted in advance. Consensus statements were developed by the working groups and then presented to the entire panel for further discussion and amendment before voting. This article presents the developed statements, including findings from the expert panel discussions, expert opinion, and a summary of evidence supporting each statement.

Abstract ES1-1: What is a HER2-positive in breast cancer in 2018?

Remarkable progress has been made in the treatment of patients with HER2-positive breast cancer since trastuzumab was approved by the U.S. Food and Drug Administration 20 years ago. Among patients with HER2-positive disease, HER2-targeted therapy has been associated with substantial improvements in overall survival in the adjuvant setting, a high rate of pathologic complete response (pCR) after neoadjuvant therapy, and improvements in survival in patients with metastatic disease. While much of these improvements in outcome is due to more effective therapies, improvements in patient selection as a result of more accurate HER2 testing has also contributed to the better prognosis of patients with this disease. Data from clinical trials examining the benefit of trastuzumab in the adjuvant setting and published in the early 2000s (e.g., NSABP B31; NCCTG 9831) demonstrated that up to 25% of community-based assays reported as HER2-positive by immunohistochemistry (IHC) and up to 15% reported as HER2-positive by fluorescence in situ hybridization (FISH) could not be confirmed upon central laboratory testing. To address this high frequency of false-positive results and to improve the accuracy of HER2 testing, the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) in 2007 published guideline recommendations for HER2 testing. These guidelines were subsequently updated in 2013 and, more recently, in 2018. Since the implementation of these guidelines, the accuracy of HER2 testing has improved. In fact, in current clinical practice, when HER2 IHC and FISH testing are performed according to the ASCO-CAP guidelines, approximately 95% of breast cancers can ultimately be categorized as either unequivocally HER2-positive or HER2-negative. In the remainder of the cases, combined IHC and FISH assay results provide a less straightforward picture of the HER2 status and, in turn, create uncertainty regarding the likelihood of benefit from HER2-targeted therapy. These include cases which on dual-probe FISH testing show: 1) HER2/CEP17 ratio >2.0 and an average HER2 copy number <4.0 signals/cell (monosomy); 2) HER2/CEP17 ratio <2.0 and an average HER2 copy number >6.0 signals/cell (polysomy); and 3) HER2/CEP17 ratio <2.0 and an average HER2 copy number >4.0 and <6.0 signals/cell. However, the most recent (2018) update of the ASCO-CAP guidelines provides pragmatic recommendations to resolve the HER2 status of such cases, and this, in turn, should result in even fewer cases in which the HER2 status remains in doubt. It should be noted, however, that not all patients whose tumors are HER2-positive by IHC and/or FISH respond similarly to HER2-targeted therapy and that some patients who initially respond subsequently develop resistance. Active efforts are underway to understand the mechanisms of de novo and acquired resistance to HER2-targeted treatments and to identify biomarkers that can predict resistance to therapy. Thus, the clinically relevant question in 2018 is not “what is a HER2-positive breast cancer ”? Rather, the question that now needs to be addressed is “which HER2-positive breast cancers will respond to HER2 targeted-treatments and to which HER2-targeted treatments are they most likely to respond? ”.

Citation Format: Schnitt S. What is a HER2-positive in breast cancer in 2018? [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr ES1-1.

Abstract P5-02-02: Second harmonic generation in combination with nuclear morphometry in the evaluation of DCIS

Purpose/Objective: Collagen is a major extracellular matrix (ECM) constituent in normal breast and is extensively remodeled in breast carcinoma. Therefore, features of remodeled collagen in the stroma adjacent to ductal carcinoma in situ (DCIS) could indicate cancer progression. The major objective of this study is to identify potential tumor-associated collagen signatures unique to DCIS that will allow us to predict progression based on the collagen texture and nuclear morphology. In this present study, we develop two image analysis pipelines (SHG Texture Extraction and H&E Nuclear Morphology Extractor) to quantify 1) stromal changes, 2) collagen signatures and 3) nuclear morphology from normal breast to DCIS in order to predict local breast cancer recurrence.

Method: We used second harmonic generation (SHG) images and H&E to analyze collagen features and to study nuclear morphology using a data set of 336 patients (from which 310 normal and 327 DCIS regions were imaged). The 336 patients were a subset of patients with pure DCIS taken from a case-control study. Clinical-pathologic factors were associated with risk of subsequent ipsilateral cancer (DCIS or invasive). The SHG framework consisted of collagen segmentation using 1) adaptive thresholding and 2) morphological operations. The H&E framework consisted of nuclear segmentation using adaptive thresholding and a maker-controlled watershed algorithm; and nuclear feature extractions including intensity, texture and morphology. Overall, the SHG framework segments collagen regions and computes textural features specifically at collagen regions. Furthermore, the H&E framework segments nuclei and computes nuclei morphology and textural features. These features were used in L1-regularized logistic regression to construct classification models to discriminate normal vs DCIS regions; and to distinguish regions from DCIS patients with vs. without local recurrences.

Results: In first experiment, we performed L1-regularized logistic regression to construct a classification model to discriminate normal vs DCIS regions. Our results suggest that using only SHG collagen features, this logistic model selected 19 significant features to build a classification model that achieved area under curve (AUC) 90% and accuracy 83% using 5-Fold cross validation. When H&E nuclei features are used, the logistic model selected 88 significant features and achieved AUC 91% and accuracy 86%. By combined both SHG and H&E features, the model achieved classification AUC 93% and accuracy 88%. By using L1-regularized logistic model with combined significant SHG and H&E features, we achieved AUC 59% with an accuracy of 61% for DCIS and recurrent DCIS regions.

Conclusions: Our study suggests that SHG and nuclear morphology features extracted from H&E can improve the classification of normal and DCIS regions. Overall, these results suggest that second harmonic generation and H&E nuclear morphology analysis could aid in the assessment of prognosis and risk of progression to invasive breast cancer.

Citation Format: Park CC, Irshad H, Ziaee S, Martin-Tuite P, Habel L, Weaver VM, Schnitt SJ, Beck AH. Second harmonic generation in combination with nuclear morphometry in the evaluation of DCIS [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-02-02.

Abstract P2-09-25: Clinical and pathologic characteristics of breast cancers determined to be HER2-positive by fluorescence in-situ hybridization (FISH) using alternative chromosome 17 probes

Background:

Based on updated 2013 ASCO/CAP guideline for HER2 testing, cases with a HER2/CEP17 ratio < 2.0 but with an average HER2 copy number > 4.0 and <6.0 signals/cell are considered equivocal. In such cases, HER2 testing using alternative chromosome 17 probes was proposed as one way to resolve the equivocal FISH results. Using the alternative probe method increases the number of cancers categorized as HER2 positive but brings to question if these cancers truly represent HER2 amplified breast cancers and derive the same benefit from anti-HER2 therapies.

Methods:

Since 2013, all breast cancers at our institution that were HER2 equivocal by traditional FISH but classified as HER2 positive using the alternative probe method were assessed for clinical and pathologic features including histologic type and grade, TNM stage, HER2: alternative probe ratio, treatment, and clinical outcome.

Results:

We identified 24 invasive breast cancers considered HER2 positive by the alternative probe method: 23 (96%) were estrogen receptor-positive (ER+) and 20 (83%) were progesterone receptor- positive. Histologically, only 2 were invasive lobular carcinomas; all others were ductal or had ductal and lobular features. Most cancers (63%) had low or intermediate histologic grade: Grade 1 (n=3); Grade 2 (n=12); Grade 3 (n=9). Clinical information was available for 18 patients: 2 had metastatic disease, 1 had a local recurrence after mastectomy and 15 patients had early stage disease; 9 with node negative disease and 6 with nodal involvement. HER2 IHC was equivocal (2+) in 16 (66.7%) cases, positive (3+) in 4 (16.7%) cases, and negative (0 or 1+) in 4 (16.7%) cases. The average HER2 copy number was 4.77, the average HER22:p53 ratio was 2.61. Repeat HER2 testing on a 2nd tumor sample was performed in 8 cases: HER2-positivity was confirmed in only 2 (25%) cases and by the alternative probe only. Treatment information was available for 17 patients: 1 had T1aN0M0 lesion and did not get chemotherapy, 16 received chemotherapy and 13 received trastuzumab-based chemotherapy. Eleven patients with early stage disease received chemotherapy and trastuzumab. Of these patients, 10/11 were ER+, 7/11 were node negative and 5/11 had grade 2 tumors, yet only one tumor was assessed by oncotype recurrence score ( RS = 29). Three patients received chemotherapy and trastuzumab in the neoadjuvant setting: 1 had a complete pathologic response, 1 a partial response, and 1 has not yet gone to surgery. One additional patient received neoadjuvant chemo alone and achieved a partial response.

Conclusions:

Breast cancers considered HER2+ by the alternative probe method but not by traditional FISH are almost always ER-positive and most have low or intermediate histologic grade. Repeat HER2 testing on a subsequent tumor sample did not confirm HER2-positivity in 75% of cases. Almost all patients with early stage disease received chemotherapy and trastuzumab based on the alternative probe results without molecular assessment to predict chemotherapy response. Intrinsic molecular subtyping using PAM50 analysis on these cancers is underway to determine how many are HER2-enriched by molecular assessment.

Citation Format: Desai NV, Torous V, Cruz C, Schnitt SJ, Tung N. Clinical and pathologic characteristics of breast cancers determined to be HER2-positive by fluorescence in-situ hybridization (FISH) using alternative chromosome 17 probes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-25.

Abstract S2-02: The landscape of somatic genetic alterations in BRCA1 and BRCA2 breast cancers

Introduction: Women carrying BRCA1 or BRCA2 germline mutations have a 45-80% lifetime risk of developing breast cancer (BC). BRCA1 and BRCA2 are perceived as bona fide tumor suppressor genes, whereby bi-allelic inactivation in tumor cells is required for tumorigenesis. Recent studies have indicated that loss of heterozygosity (LOH) of the wild-type allele of BRCA1 may be heterogeneous and constitute a late event. Therefore, additional somatic events prior to full BRCA1/2 inactivation may be required for tumorigenesis. Given that the somatic events that result in the development of BRCA1/2-BCs and their chronology are not understood, here we sought to define the genomic landscape of BRCA1/2-BCs and whether LOH of BRCA1/2 wild-type allele and/or mutations affecting additional tumor suppressor genes would be clonal or subclonal in these cancers.

Methods: We retrieved 29 BRCA1-BCs and 10 BRCA2-BCs from the Pathology Departments of the authors' institutions. DNA extracted from microdissected tumor and normal breast samples was subjected to targeted capture massively parallel sequencing using either the MSK-IMPACT assay or an assay targeting all exons of 254 genes recurrently mutated in BC or related to DNA repair. Somatic single nucleotide variants, small insertions and deletions and copy number alterations affecting genes present in both sequencing assays (111 genes) were defined using state-of-the-art bioinformatics algorithms. ABSOLUTE and FACETS were employed to define clonal (i.e. present virtually in 100% of the cancer cells of a given case) and subclonal mutations and the presence of LOH of the BRCA1 and BRCA2 wild-type alleles.

Results: Our analysis revealed bi-allelic inactivation of BRCA1 in 28 of 29 BRCA1-BCs (93% harbored LOH of the BRCA1 wild-type allele and 3% harbored a second somatic BRCA1 pathogenic mutation). The only BRCA1-BC lacking bi-allelic inactivation of BRCA1 was an estrogen receptor-positive lobular carcinoma, lacking genomic features consistent with homologous recombination DNA repair defects, diagnosed at 62 years of age. Bi-allelic inactivation of BRCA2 was found in all cases (100% of harbored LOH of the BRCA2 wild-type allele). A clonal somatic 'second hit' resulting in bi-allelic inactivation of BRCA1 or BRCA2 was detected in 76% and 100% of BRCA1-BCs and BRCA2-BCs, respectively. In BRCA1-BCs, TP53 mutations were detected in 76% of cases, and these mutations were found to be clonal in 58% of cases. The repertoire of somatic mutations affecting BRCA1-BCs included clonal somatic mutations or homozygous deletions of known tumor suppressor genes, such as PTEN, RB1, CDKN2A and NF1. In contrast, only 10% of the BRCA2-BCs harbored TP53 somatic mutations. Though clonal somatic mutations in several cancer genes were detected, 40% of BRCA2-BCs had no mutations affecting the cancer genes analyzed.

Conclusions: Bi-allelic inactivation of BRCA1 and BRCA2 are frequent events in BRCA1-BCs and BRCA2-BCs, respectively. In a subset of BRCA1-BCs, however, the second 'hit' appeared to be subclonal, whereas mutations affecting TP53 and other tumor suppressor genes were clonal, supporting the notion that at least in a subset of these tumors, loss of the wild-type allele of BRCA1 may be preceded by inactivation of another tumor suppressor gene.

Citation Format: Geyer FC, Burke KA, Macedo GS, Piscuoglio S, Ng CK, Martelotto LG, Papanastatiou AD, De Filippo MR, Schultheis AM, Brogi E, Robson M, Wen YH, Weigelt B, Schnitt SJ, Tung N, Reis-Filho JS. The landscape of somatic genetic alterations in BRCA1 and BRCA2 breast cancers [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S2-02.

Abstract P2-12-01: Comprehensive genomic profiling of 34 cases of breast angiosarcoma

Background: Angiosarcoma of the breast (BAS) is a rare but lethal neoplasia, either arising de novo or secondary to radiation therapy, with incidence of the latter disease increasing. We queried a database of more than 70,000 advanced cancer patients assayed with comprehensive genomic profiling (CGP) in the course of clinical care to uncover the frequency, type and associated genomic alterations (GA) in BAS and to highlight possible routes to benefit from targeted therapy.

Methods: CGP was performed for 34 BAS cases using a hybrid-capture, adaptor ligation based next generation sequencing assay of up to 315 genes to a mean coverage depth of >500X. The results were analyzed for base substitutions, short insertions and deletions, selected rearrangements, and copy number changes. RNA sequencing for 265 genes was also performed for 24 cases. Limited clinical histories from submitted pathology reports were reviewed under IRB permission.

Results: Clinical specimens from 34 BAS patients, all females, were assayed. The cases harbored 87 total GA for a mean of 2.59 per case, 25% of which were copy number amplifications. The most commonly altered genes were MYC (41%, 14/34), PIK3CA (26%, 9/34), and KDR (26%, 9/34). All MYC alterations were amplifications with a mean copy number of 39, and alterations in other MYC family members (MYCN and MYCL1) were not observed. KDR was recurrently altered as T771R (7/9) and T771K (1/9) and amplified in one case (1/9).

MYC and KDR alterations were mutually exclusive (p<0.0001). 6/14 MYC amplified cases had prior histories of breast carcinoma, with 3/6 noted as being treated with radiation therapy. For the remainder of MYC amplified cases (8/14), no relevant clinical history was available.

Two cases harboring gene fusions were identified including CIC-MEGF8 and NTRK1-PEAR1. Two rearrangements of potential functional significance including CIC-DEDD2 and HT-ALK (exon1 HT - exon5-29 ALK including kinase domain) were also observed. The case harboring HT-ALK also had MYC amplification and known prior radiation therapy. Two other MYC amplified cases also harbored targetable kinase alterations, including FLT4 amplification (described as targetable in Ravi et al JNCCN 2016) and FGFR3 S249C, a known activating mutation.

Conclusions: MYC amplification defines over 40% (14/34) of advanced BAS cases. Of MYC amplified cases, 28% (4/14) harbored targetable alterations of tyrosine kinases including a potential novel ALK fusion. FLT4 amplification only co-occurred with MYC amplification, but this result was not statistically significant in this small series. KDR and MYC alteration were mutually exclusive, and 45% of non-MYC altered cases (9/20) harbored KDR alterations, which were predominantly mutations of T771. Further clinico-pathologic correlation, particularly history of radiation therapy, will be explored in this series, as well defining BAS that harbor neither MYC nor KDR alterations.

Citation Format: Ravi V, Madison R, Schrock AB, Cote G, Millis S, Alvarez R, Choy E, Katz D, Chung J, Gay L, Miller VA, Ross JS, Ali SM, Schnitt S. Comprehensive genomic profiling of 34 cases of breast angiosarcoma [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-12-01.

Abstract ES02-1: Pathology and biology of early breast lesions

It has been almost three decades since Dupont and Page published their seminal study relating breast cancer risk to the histologic findings in benign breast biopsies. Their initial observation, that proliferative lesions without atypia are associated with a 1.5-2-fold increase in breast cancer risk whereas atypical hyperplasias are associated with a 4-5-fold increase in risk, has been confirmed by other groups, including the Breast Cancer Detection Demonstration Project, the Nurses’ Health Study and the Mayo Clinic, among others. In aggregate, these groups have evaluated the relationship between the findings in benign breast biopsies and breast cancer risk in over 15,000 women and have additionally shown that several clinical, epidemiologic and histologic factors such as patient age, menopausal status, family history, time since biopsy, type and extent of atypical hyperplasia, and even the extent of involution of normal breast lobules modify the breast cancer risk among women with benign breast disease. More recent studies have examined the expression of various biomarkers and molecular alterations to determine their impact on breast cancer risk among women with benign breast lesions. While the expression of some biomarkers (including ERa, ERβ, TGFβ receptor II, COX2, and Ki67) has been reported to further stratify risk among women with proliferative breast lesions with and without atypia, all of these studies are limited by small patient numbers, due in part to the difficulty in capturing the microscopic lesions of interest for biomarker analysis. Given these limitations, an alternative approach is to study expression of biomarkers and molecular alterations in histologically normal breast tissue since normal epithelium is typically more abundant in benign breast biopsies than is lesional tissue. Using this approach, one recent study suggested that cytoplasmic expression of IGF-1R in normal breast epithelial cells identifies woman with benign breast disease at a particularly high risk for the subsequent development of breast cancer. This raises the possibility that targeting the IGF-1 pathway could be a novel strategy for breast cancer risk reduction. Other studies evaluating gene expression in normal breast epithelium have identified signatures that distinguish histologically normal breast epithelium obtained from reduction mammaplasty specimens from that obtained from breast cancer patients and, further, that distinguish normal breast epithelium in breasts with ER-positive cancers from that in breasts with ER-negative tumors. Data such as these raise the possibility that there may be identifiable, subtype-specific changes in gene expression within normal breast epithelial cells before histologic abnormalities are evident. It is likely that an integrated approach that combines epidemiology, histopathology, biomarker analysis and evaluation of molecular alterations will permit refinement of breast cancer risk assessment beyond that currently available and will, in turn, lead to new risk reduction strategies.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr ES02-1.

Abstract S3-06: Emergence of constitutively active estrogen receptor mutations in advanced estrogen receptor positive breast cancer

Introduction: The lack of estrogen receptor (ER) expression is the primary cause of de novo resistance of breast cancers to endocrine therapy. In contrast, in most cases of acquired endocrine resistance, ER is expressed and other mechanisms of resistance have been proposed, such as ER mutations. Pre-clinical studies demonstrated a small number of specific point mutations that can enhance ER function. However, the studies on clinical samples performed in the 1990's were limited by small sample size, lack of detailed clinical correlation and lacked the sensitivity of next-generation sequencing (NGS). Therefore, in this study we sought to comprehensively investigate the frequency and functional significance of ER mutations throughout the progression of breast cancer from primary disease to advanced metastatic disease using targeted NGS.

Methods: In this retrospective study, a total of 249 tumor specimens were analyzed. The specimens include 134 ER positive and, as controls, 115 estrogen receptor negative tumors. The estrogen receptor positive samples consist of 58 primary breast cancers and 76 metastatic sample. All tumors were sequenced with high coverage using NGS targeting the coding sequence of ER and an additional 181 cancer-related genes.

Results: Recurring somatic mutations at codons 537 and 538 within the ligand-binding domain of the estrogen receptor were detected in ER positive metastatic tumors. Overall, the frequency of these mutations was 12% (95% CI 6%-21%) in metastatic patients compared with none in the primary cases. In total there were 9 recurring somatic mutations; Y537C (11%), Y537N (33%), Y537S (22%) and D538G (33%). In addition in a small number of paired primary and metastatic samples from the same patient, these mutations were found only in the metastatic specimens. In a subset of heavily pre-treated patients the frequency was 20% (5/25, 95% CI 7%-41%). ER activating mutations were not detected in any stage of ER negative disease. ER alterations were not mutually exclusive with any of the other commonly altered genes and of the most frequently altered genes, all but ER alterations displayed similar frequencies across primary and metastatic specimens. Functional studies in cell line models demonstrated that these ER mutations render ER constitutively active and confer resistance to hormone deprivation, tamoxifen and fulvestrant.

Conclusions: Herein, we reveal functional ER mutations as potential drivers of endocrine resistance during the progression of ER positive breast cancer. The absence of detectable mutations in the primary tumors suggests clonal evolution as the mechanism of resistance. Thus, these mutations have the potential to be an important genetic biomarker of endocrine resistance in ER positive metastatic breast cancer and could assist in clinical decision making as disease progresses. Our findings also underscore the value of repeated biopsies of metastatic lesions. Lastly, since the frequencies of these mutations are substantial when sensitive testing methods are used in the correct clinical context, pre-clinical and clinical studies to identify novel therapeutics that can overcome this resistance are warranted.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S3-06.

Abstract PD01-08: Differences in estrogen receptor signaling in non-malignant primary ER-positive breast epithelial cells and breast cancer

Background: The estrogen receptor (ER) is expressed in ∼70% of sporadic breast cancer and activates genes driving cell proliferation and tumorigenesis. We have previously performed genome-wide analysis of ER binding sites in MCF-7 breast cancer cells, and identified distinct mechanisms of ER signaling. We have also previously used EpCAM and CD49f as markers to enrich for viable ER-positive (ER+) cells obtained from non malignant breast tissue. Here, we seek to elucidate differences in ER signaling between non-malignant and ER+ breast cancer cells.

Methods: Primary breast epithelial cells were obtained from patients undergoing reduction mammoplasties and surgical excision of ER+ breast cancer. After dissociation of breast reductions into a single-cell suspension, ER+ mature luminal (ML; EpCAM+CD49f−) and luminal progenitor (LP; EpCAM+CD49f+) subpopulations were obtained by flow cytometry. Following estrogen stimulation, RNA was extracted for gene microarray analysis. ER chromatin immunoprecipitation and DNA sequencing (ChIP-seq) was performed. These results were compared to MCF-7 breast cancer cells.

Results: Reduction mammoplasty and ER+ breast cancer tissues were analyzed, and compared to MCF-7 cells. Gene expression profiles were different between non-malignant tissue and ER+ breast cancer cells following estrogen stimulation, with a 2–3 fold higher number of ER regulated genes in ER+ breast cancer compared to ER+ non malignant cells, and few overlapping estrogen regulated genes. Genes that promotes cell cycling and cell proliferation were downregulated in non-malignant tissue, but were upregulated in breast cancer cells (P < 10–5). CYP1A1, a major estradiol metabolizing enzyme, was upregulated in normal cells but downregulated in ER+ breast cancer cells. Motif analysis of ER ChIP-seq data in normal and ER+ breast cancer tissues demonstrated an enrichment of ER motifs in the overlapping sites and an enrichment of FOXA1 motifs in ER+ breast cancer cells and TCF12 motifs in non-malignant ER+ epithelial cells.

Conclusions: There are contrasting differences in ER signaling between normal mammary and breast cancer cells, with estrogen having anti-proliferative effects in normal luminal cells compared to pro-proliferative effects in breast cancer. ER ChIP-Seq has identified TCF12 as a major co-factor in non-malignant breast tissue whilst FOXA1 is a major co-factor in ER+ breast cancer. Our data provides evidence for key alterations in ER-signaling during tumorigenesis, and identifies potential mechanisms to target cancer specific ER signaling.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD01-08.

P5-01-13: High Levels of Nuclear Heat Shock Factor 1 (HSF1) Are Associated with Poor Prognosis in Breast Cancer: Results from the Nurses' Health Study

Purpose: Heat shock factor 1 (HSF1) is the master transcriptional regulator of the cellular response to heat and a wide variety of other stressors. We previously reported that HSF1 promotes the survival and proliferation of malignant cells. At this time, however, the clinical and prognostic significance of HSF1 in cancer is unknown.

Patients and methods: Breast cancer samples from 1,841 participants in the Nurses’ Health Study (NHS) were scored for levels of nuclear HSF1. Associations of HSF1 status with clinical parameters and survival outcomes were investigated by Kaplan-Meier analysis and Cox proportional hazard models. The associations were further delineated by Kaplan-Meier analysis using publicly available mRNA expression data.

Results: Nuclear HSF1 levels were elevated in ∼80% of in situ and invasive breast carcinomas. In invasive carcinomas, HSF1 expression was associated with high histologic grade, larger tumor size, and nodal involvement at diagnosis (P<0.0001). Overall, in multivariate analysis, high-HSF1 levels were associated with increased breast cancer-specific mortality (HR, 1.62; 95% CI, 1.21−2.17). This association was seen in the ER-positive population (HR, 2.10; 95% CI, 1.25−2.47), even in early-stage lymph node negative cases (HR, 1.98; 95% CI, 1.17−3.33). In public expression profiling data, high-HSF1 mRNA levels were also associated with an increase in ER-positive breast cancer-specific mortality.

Conclusions: Increased HSF1 is associated with reduced survival in breast cancer. The findings indicate that HSF1 should be evaluated prospectively as an independent prognostic indicator in ER-positive breast cancer and that HSF1 may provide a useful therapeutic target.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-01-13.

P4-11-02: Insulin-Like Growth Factor-1 (IGF-1), Insulin-Like Growth Factor Binding Protein-3 (IGFBP-3) and Lobule Type among Women in the Nurses' Health Study II (NHS II)

In a previous analysis of women enrolled in NHSII, we found that among women diagnosed with benign breast disease (BBD), those with predominant type 1/no type 3 lobules were at lower risk of subsequent breast cancer compared to women with other lobule types. Additionally, studies in animal models suggest that higher levels of IGF-1, a polypeptide hormone involved in the proliferation/differentiation of normal mammary epithelium, may inhibit involution of breast lobules. However, the interaction between IGF-1 levels and lobule types in determining breast cancer risk has not been previously evaluated. Therefore, we examined the association between IGF-1 levels and lobule type among women with BBD.

Methods: We conducted a cross-sectional study among 484 women in NHSII with biopsy-confirmed BBD between 1993–2001 who had blood samples available for determining levels of IGF-1 and IGFBP-3. A pathologist, blinded to exposure status, classified lobule type on biopsy slides according to the number of acini per lobule (type 1 < 12; type 2∼50; type 3∼80 acini). Lobule type was classified into (1) predominant type 1/no type 3 lobules or (2) other lobule types. Multivariate logistic models were used to assess the associations between plasma IGF-1, IGFBP-3, and IGF-1/IGFBP-3 levels with lobule type. Models were adjusted for age, IGF-1 batch and additional potential confounders in secondary analyses.

Results: In univariate analyses, older age at biopsy, higher body mass index, postmenopausal status, nulliparity, and lower IGF-1 levels were associated with predominant type1/no type 3 lobules (p<0.05). In multivariate logistic models adjusting for age, higher IGF-1 levels were associated with a decreased risk of predominant type 1/no type 3 lobules (OR quartile 4 vs. quartile 1 = 0.35, 95%CI: 0.15−0.81). Greater IGF-1/IGFBP-3 ratio was also associated with a decreased risk of predominant type1/no type 3 lobules (OR quartile 4 vs. quartile 1 = 0.24, 95%CI: 0.10−0.57).

Abstract P1-15-03: Eight-Year Update of a Prospective Study of Wide Excision Alone for Ductal Carcinoma In Situ (DCIS) of the Breast

Background: The need for radiation therapy (RT) in conservatively managed DCIS is a source of ongoing debate. This is an updated analysis of a phase II prospective study of wide excision alone for DCIS. The study was activated in May 1995 and closed in July 2002 following accrual of 158 patients because the number of local recurrences (LR) met the predetermined stopping rules. The objective of the analysis is to update the distribution and cumulative incidence of events (LR, contralateral breast cancer [CBC], second malignancy and death from other causes). Materials and Methods: A total of 158 patients had DCIS with predominant nuclear grade 1 or 2, a mammographic extent of ≥2.5 cm, and excision with final microscopic margins of ≥1 cm or a re-excision without residual DCIS. Tamoxifen was not permitted. The results presented are from the 8-year analysis (8-year minimum potential follow-up time). Twenty-six patients without recurrence who were followed less than 8 years were excluded from the analysis as were 7 first events (4 LR) that occurred beyond 8 years of follow-up; the analysis thus includes 132 patients and 36 first events. Cumulative incidence curves were generated to assess the rates of LR or other events. Median follow up time was 10 years. Results: Overall, 36/132 patients (27%) had a first event as of April 2010. Of these 36 events, 19 were LR, 13 were CBC, 1 was a second malignancy, and 3 were deaths from other causes. Of the 19 LR, 13 (68%) were DCIS only and 6 (32%) were invasive. Fourteen occurred in the same quadrant and 5 were elsewhere in the ipsilateral breast. The 8-year estimated cumulative incidence of LR was 14.4% (95% CI: 8.4-20.4%). For all other events, the 8-year estimated cumulative incidence was 12.9% (95% CI: 3.6-13.1%).

The estimated annual percentage rates of LR, CBC, and other events were 2.1%, 1.5% and 0.4%, respectively.

Discussion: The results of this prospective study demonstrate a substantial and ongoing risk of LR and CBC in patients with small, nuclear grade 1 or 2 DCIS treated with wide excision with margins of ≥1cm in the absence of RT. Most LRs occurred in the same quadrant, rather than elsewhere in the breast, suggesting that excision alone is inadequate even for this highly selected population. Further study is warranted to determine if there is a subgroup of DCIS patients with nuclear grade 1 or 2 disease who are at low enough risk of LR following wide excision that RT can be omitted safely.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-15-03.

Estrogen Rececptor (ER)-Positive Breast Cancers in BRCA1 Mutation Carriers: Mutation-Related or Sporadic?

Background: Most invasive breast cancers (IBC) in BRCA1 mutation carriers are ER negative (-) and have a basal-like phenotype by expression array analysis. These tumors also have a characteristic constellation of histologic features including high grade, high mitotic rate, prominent lymphoid infiltrate, circumscribed or pushing margins, and geographic necrosis or a central fibrotic focus and typically lack ER, PR and HER2 expression (triple negative). ER positive (+) breast cancers also occur in women with germline BRCA1 mutations, but these tumors are less frequent and less well characterized. We previously reported that ER+ BRCA1-associated IBC show a wider spectrum of histologic types and grades than ER- cancers that occur in these patients. We raised the possibility that at least some ER+ BRCA1-associated IBC may be sporadic rather than mutation-related. However, it is not known how the features of these ER+ BRCA1-associated IBC compare with those of sporadic ER+ IBC.Design: To address this issue, we performed a case-control study of 60 ER+ BRCA1-associated IBC (cases) matched on age and year of diagnosis with 174 ER+ sporadic breast cancers (controls). Histologic sections of cases and controls were reviewed and the pathologic features were compared with each other as well with those of 85 ER- IBC that developed in BRCA1 mutation carriers.Results: Histologic features are summarized in the Table. When compared with ER+ controls, ER+ BRCA1-associated IBC were significantly more likely to be invasive ductal carcinomas (78% vs 58%;p=0.005), histologic grade 3 (47% vs 27%;p=0.006), and to have a high mitotic rate (29% vs 9%;p=0.0003). However, all of these features were significantly less frequent in ER+ BRCA1-associated IBC than in ER- BRCA1-associated IBC (p<0.001 for all comparisons). ER+ BRCA1-associated IBC and ER+ controls were not significantly different from each other with regard to the frequency of moderate-severe lymphoid infiltrate, the presence of geographic necrosis or the presence of a fibrotic focus, but the frequency of all of these features in both groups was significantly lower than in ER- BRCA1-associated IBC (p<0.01 for all comparisons). ER+ ControlsER+ BRCA1ER- BRCA1 N=174N=60N=85Histologic Type   Invasive Ductal58%78%96%Other42%22%4%Histologic Grade   327%47%96%1 or 273%53%4%Mitotic Rate   ≥10/10 HPF9%29%93%<10/10 HPF91%71%7%Tumor Margin   Invasive96%90%37%Pushing/Circumscribed4%10%63%Lymphoid Infiltrate   Moderate-Severe16%7%30%Other84%93%70%Fibrotic Focus   Present7%12%56%Absent93%88%44%Geographic Necrosis   Present2%5%50%Absent98%95%50% Conclusions: ER+ breast cancers arising in women with BRCA1 germline mutations appear to be pathologically "intermediate" between ER- BRCA1-associated breast cancers and ER+ sporadic breast cancers. This raises the possibility that some ER+ BRCA1-associated invasive breast cancers are mutation-related and others are sporadic or that there is a unique mechanism by which ER+ cancers develop in mutation carriers. Immunophenotypic and molecular studies are in progress to further characterize this interesting group of tumors.This work was supported by a grant from the Breast Cancer Research Foundation.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5162.

DNA repair protein biomarkers in triple negative breast cancer

Abstract #1064

Introduction: Triple negative breast tumors form a distinct, aggressive, subgroup of breast cancers that exhibit a high degree of genomic instability and have many phenotypic similarities to BRCA1 deficient tumors. These observations suggest that aberrant DNA repair may be involved in triple negative tumor carcinogenesis. We profiled tumor DNA repair capacity using immunohistochemistry in order to develop prognostic biomarkers and suggest targets for novel therapies.
 Methods: We identified 143 previously treated women with triple negative breast cancers and used their archived, formalin-fixed, paraffin-embedded primary excision biopsies to create a tissue microarray (TMA). The TMA was stained using antibodies against proteins in various DNA repair pathways including XPF, FANCD2, PAR, MLH1, and MK2. Stained tissue was evaluated using machine-based image analysis and scoring that represented both the intensity and quantity of positive tumor nuclei. Biomarker scores and clinical data were assessed for correlations with outcome. Patients were randomized into training and test cohorts for the development of a multiple marker model. A set of critical threshold marker values were determined that maximally separated the training samples into low and high risk recurrence groups. Training set thresholds and marker combinations were applied towards the test set. Kaplan-Meier and Cox proportional hazards were used to test time to recurrence.
 Results: Clinical data for 115 patients with primary treatment data was available with a median follow up of 58 months. There were 37 recurrences: 18 were distant first, 12 were local first and 7 were simultaneous. Low XPF (p=0.002), pMK2 (p=0.02), MLH (p<0.001) and FANCD2 (p=0.05) were associated with shorter time to recurrence. In the training cohort, the high-risk group defined by a four marker model had a relative risk of recurrence of 3.0 (p<0.00001) and shorter median time to recurrence than the low risk group (13.1 months versus not reached). This was superior to single markers and to other markers such as P53 (p = 0.02) or Ki67 (p = 0.07). In the test set, the model produced similar results with a relative risk of 2.1 (p=0.029) for the high-risk group and shorter median time to recurrence (14.1 months versus not reached).
 Conclusions: Triple negative breast cancers show variable expression of proteins involved in DNA repair. Levels of four DNA repair proteins correlated significantly with recurrence free survival, and were used to develop a DNA repair profile model in a training set which was prognostic in a test set. DNA repair biomarker panels may be useful as prognostic or predictive indicators as well as suggest possible targets for novel therapies such as PARP inhibition. Further study of the model in another validation set with other clinical variables is warranted.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1064.

Defining breast cancer prognosis based on molecular phenotypes: results from a large cohort study

Abstract #1068

Aim
 Identification at the molecular level of breast cancers sub-types associated with different clinical outcomes would be of great value to help individualize therapeutic strategies and, in turn, improve survival. With large sample size, long follow-up, and geographical spread of the population any results derived from analysis of the Nurses' Health Study (NHS) data set may be more generalizable to the U.S population. Thus the purpose of this study was to define the survival outcomes associated with distinct molecular phenotypes of invasive breast cancer in women identified from the NHS.
 Methods
 2013 women enrolled in the NHS (1976-1996) with invasive non-metastatic breast cancer whose breast tumor samples were available for inclusion in tissue microarrays and subsequent immunohistochemical (IHC) analysis form the study population. Tumors were classified into one of 5 categories based on results of IHC assays for estrogen receptor (ER), progesterone receptor (PR), HER2, cytokeratin (CK) 5/6, and epidermal growth factor receptor (EGFR) as follows: 1) Luminal-A (ER and/or PR +ve and HER2 -ve), 2) Luminal-B (ER and/or PR +ve and HER2 +ve), 3) HER2 subtype (HER2 +ve with both ER and PR -ve), 4) Basal-like (-ve for ER, PR and HER2 and +ve for either CK5/6 and/or EGFR), 5) unclassifiable (-ve for all markers). Overall survival (OS), breast-cancer-specific survival (BCS) and recurrence-free survival (RFS) were estimated using the Kaplan-Meir product limit method and compared across groups using the log rank statistic. Cox-proportional hazards models were fitted to determine the association of molecular phenotype with survival outcomes after adjusting for age at diagnosis, stage, lymph nodes, tumor size, grade and body mass index at diagnosis.
 Results
 Median age at diagnosis was 57 years (34 – 75 years) with a median follow-up of 14 years. 1490 (74%) tumors were classified as luminal-A, 99 (4.9%) were classified as luminal-B, 106 (5.27%) were of HER2 subtype, 219 (10.9%) were classified as basal-like and 99 (4.9%) tumors were unclassifiable.726 (36%) patients had died of any cause, 433 (21.5%) had died of a breast cancer related event, and 459 (22.8%) experienced a recurrence. Five-year BCS for patients with luminal-A, luminal-B, HER2 , basal-like and unclassifiable tumors was 94%, 82%, 73%, 82% and 75% respectively (p<0.001). In the fully adjusted multivariable model compared to patients with luminal-A tumors patients with luminal-B (HR 1.73, 95% 1.18-2.53), HER2 (HR 1.39, 95% CI 0.97-1.20), basal-like (HR 1.50, 95% 1.32-1.20) and unclassifiable (HR 1.89, 95% CI 1.30-2.74) tumors had lower BCS. Similar trends were observed for OS and RFS.
 Conclusions
 Compared to women who have luminal-A tumors those with luminal-B, HER2 subtype, basal-like and unclassifiable tumors had a worse prognosis. A fifth, unclassifiable sub-group was identified that has survival outcomes similar to and may represent a subtype of basal-like tumors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1068.

Characterization of estrogen receptor-positive breast cancers in BRCA1 mutation carriers

Abstract #1105

Background: Invasive breast cancers (IBC) in BRCA1 mutation carriers are usually estrogen receptor (ER) negative (-) and more than 80% have a basal-like molecular phenotype. These tumors are typically poorly differentiated invasive ductal carcinomas with a high mitotic rate and frequently show a prominent lymphoid infiltrate, pushing or circumscribed margins, and geographic necrosis or a central fibrotic focus. However, some women with BRCA1 germline mutations develop ER positive (+) cancers; little is known about the characteristics of the ER+ tumors in this group.
 Design: We identified 41 ER+ IBC that developed in women with BRCA1 germline mutations with available pathologic material for review. The histologic features were analyzed in detail and compared with those of 45 ER- IBC that developed among BRCA1 mutation carriers.
 Results: Mean patient age was 46y for ER+ and 45y for ER- cases. Ninety percent of the ER+ cases and all the ER- cases were invasive ductal carcinomas or invasive carcinomas with ductal and lobular features. There were 2 mucinous and 2 tubular carcinomas in the ER+ group. The ER+ cancers exhibited a range of histologic grades: 12 (29.3%) were grade I, 10 (24.4%) grade II, and 18 (43.9%) grade III (1 case of microinvasive carcinoma could not be graded). In contrast, 43 of the 45 ER- cancers were grade III (95.6%) and 1 (2.2%) grade II (1 case of microinvasive carcinoma could not be graded). Histologic features commonly seen in association with ER- BRCA1 mutation-associated IBC were compared between the two groups and the results are summarized in the table.
 
 Of note, a brisk mitotic rate, pushing margin, and the presence of geographic necrosis/central fibrosis were all significantly more common in ER- than in ER+ tumors.
 Conclusions: To our knowledge, this study is the first to document in detail the histologic features of the uncommon ER+ IBC occurring in BRCA1 mutation carriers. Our observations suggest that ER+ IBC in BRCA1 mutation carriers represent a morphologically diverse group. This raises the possibility that at least some ER+ IBC that develop in women with germline BRCA1 mutations may be sporadic rather than BRCA1-associated. We are currently analyzing these lesions with a panel of biomarkers and assays for loss of heterozygosity at the BRCA1 mutation sites to further address this important issue.
 This work was supported by a grant from the Breast Cancer Research Foundation.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1105.

Breast epithelial differentiation is altered in BRCA1mut/+ carriers prior to the onset of cancer and contributes to the basal tumor phenotype

Abstract #3083

Human breast tumors are broadly divided into either luminal-like or basal-like cancers. This distinction is significant since basal-like tumors are more aggressive and afford a poor patient prognosis relative to luminal-like tumors. For reasons that are unclear, germline mutations in BRCA1 strongly predispose for poor prognosis basal-like tumors. The predisposition for basal-like tumors in BRCA1mut/+ patients could be due to (1) differences in underlying target cell populations between BRCA1mut/+ and BRCA1+/+ women or (2) differences in the genetic mutations arising within a single shared target cell type. This basic question has remained unresolved due to a lack of experimental models in which it can be addressed. We describe here a novel in vivo breast cancer system that enables the generation of tumors by introducing oncogenes into normal breast epithelium derived directly from human breast tissue. This system is unique in that it enables human-derived epithelial cells to be sorted for cell surface markers and transformed without requiring in vitro culture prior to implantation in vivo. Using this experimental system, we show that epithelial cells from BRCA1mut/+ patients give rise to tumors that exhibit multiple features of basal differentiation, in contrast to epithelial cells transformed with identical oncogenes from BRCA1+/+ patients. We show further that non-cancerous epithelial cells from BRCA1mut/+ patients already exhibit atypical differentiation even prior to the onset of cancer, in contrast to cells from BRCA1+/+ women. Remarkably, some of these differences are observable in the context of unperturbed breast tissue obtained from disease-free BRCA1mut/+ and BRCA1+/+ patients. Collectively, these findings show that the increased incidence of basal-like tumors in BRCA1mut/+ patients is a reflection of the altered differentiation of breast epithelial cells in BRCA1mut/+ patients.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3083.

Papillary lesions of the breast: selected diagnostic and management issues

The assessment and categorization of papillary lesions remains one of the most challenging areas in breast pathology. In this review, we will focus on several diagnostic and management issues related to papillary breast lesions that are frequently encountered in daily practice. These include: (i) the distinctions among papillomas with atypia (atypical papillomas), papillomas with ductal carcinoma in situ, and papillary ductal carcinoma in situ; (ii) recent developments in our understanding of encapsulated ('intracystic') papillary carcinomas and solid papillary carcinomas; and (iii) the impact of core needle biopsy on management decisions and specimen evaluation. The role of immunohistochemistry in the evaluation of these lesions, particularly the role of myoepithelial cell markers, will be emphasized.

Germline E-cadherin mutations in familial lobular breast cancer

BACKGROUND

The cell surface glycoprotein E-cadherin (CDH1) is a key regulator of adhesive properties in epithelial cells. Germline mutations in CDH1 are well established as the defects underlying hereditary diffuse gastric cancer (HDGC) syndrome, and an increased risk of lobular breast cancer (LBC) has been described in HDGC kindreds. However, germline CDH1 mutations have not been described in patients with LBC in non-HDGC families. This study aimed to investigate the frequency of germline CDH1 mutations in patients with LBC with early onset disease or family histories of breast cancer without DGC.

METHODS

Germline DNA was analysed in 23 women with invasive lobular or mixed ductal and lobular breast cancers who had at least one close relative with breast cancer or had themselves been diagnosed before the age of 45 years, had tested negative for a germline BRCA1 or BRCA2 mutation, and reported no personal or family history of diffuse gastric cancer. The full coding sequence of CDH1 including splice junctions was amplified using PCR and screened for mutations using DHPLC and sequencing.

RESULTS

A novel germline CDH1 truncating mutation in the extracellular portion of the protein (517insA) was identified in one woman who had LBC at the age of 42 years and a first degree relative with invasive LBC.

CONCLUSIONS

Germline CDH1 mutations can be associated with invasive LBC in the absence of diffuse gastric cancer. The finding, if confirmed, may have implications for management of individuals at risk for this breast cancer subtype. Clarification of the cancer risks in the syndrome is essential.

Prevalence of BRCA1 mutations in triple negative breast cancer (BC)

508

Background: 90% of BCs in women with germline BRCA1 mutations are ER, PR and HER2 negative (so-called “Triple Negatives”), and 80–90% of triple negative BCs are “basal-like” by DNA microarray and IHC analysis. Prevalence of germline BRCA1 mutations among women with triple negative BC may therefore, be elevated, and underestimated by available calculation models, which do not take tumor features into account. Methods: We randomly identified 200 women from the Dana-Farber/Harvard Cancer Center SPORE annotated specimen bank with histologically confirmed primary invasive, ER, PR and HER2 negative BC. Myriad prevalence tables for BRCA1 were used to estimate the probability that each subject carried a BRCA1 mutation according to age at BC diagnosis, family and personal history of breast and/or ovarian cancer, and Ashkenazi Jewish ancestry. Full sequencing analysis for BRCA1 germline mutations is in progress. Results: The median age at diagnosis of triple negative BC was 49 years (range 26–79). The majority of tumors were high grade (89%) ductal (95%) carcinomas; median tumor size was 2 cm, 50% had positive nodes. 3 patients had a personal history of ovarian cancer and 13 reported Ashkenazi Jewish ancestry. 44% had at least one first or second degree relative with BC; 12% had at least one relative with ovarian cancer. The estimated probability of detecting a BRCA1 mutation according to the Myriad tables ranged from 0.019 to 0.386 (median 0.039): the total expected number of BRCA1 mutations was 11. In a subgroup of 23 patients (12%), who had undergone clinical testing, 2.7 BRCA1 and 1.4 BRCA2 mutations were expected according to the Myriad tables. However, 9 deleterious BRCA1 mutations (39.1%) were found; 2 patients had a BRCA2 mutation (8.7%). Conclusions: The relative excess of BRCA1 mutations in a small group of patients with triple negative BC suggests that established risk factors alone may underestimate the prevalence of BRCA1 mutations among women with this BC subtype. We anticipate that complete BRCA1 analysis of our entire group will more definitively estimate the prevalence BRCA1 mutations among women with triple negative BC.

No significant financial relationships to disclose.

Traditional and newer pathologic factors

There has long been a pressing clinical need to identify prognostic and predictive factors for patients with breast cancer. Although numerous candidate biological and molecular markers have been identified during the last two decades, traditional factors such as lymph node status, tumor size, histologic type, histologic grade, and hormone receptor status remain the most useful indicators of prognosis and therapeutic response. A major obstacle to the translation of research advances into clinically useful prognostic and predictive markers has been the considerable methodologic variability used in the evaluation of the newer markers. It is now generally accepted that, to be useful in patient management, a putative prognostic or predictive marker must have clinical importance, independence, significance, and standardization with regard to methods, interpretation, and reporting. It is hoped that recognition and adoption of these criteria will serve to clarify the value of newer biologic and molecular markers.

Benign breast disease and breast cancer risk: potential role for antiestrogens

Evidence from clinical follow-up studies has indicated that there is a relationship between the presence of histologically proven benign breast disease and breast cancer risk, and that the risk varies according to the histological category of benign breast disease and hormonal status. The risk associated with these histological factors appears to be equal in both breasts, suggesting that these factors are best considered markers of generalized increased breast cancer risk rather than direct precursor lesions. A number of interesting observations gleaned from the Nashville Study, the Breast Cancer Detection Demonstration Project and the Nurses' Health Study, among other studies, provide evidence of an interaction between these histological risk factors and estrogen in determining the level of breast cancer risk. In the National Surgical Adjuvant Breast Project P-1 trial, tamoxifen was associated with an 86% reduction in breast cancer risk among a small subset of women with biopsy-proven atypical hyperplasia. Taken together, these observations strongly suggest that there is an interaction between estrogen and histological factors in determining breast cancer risk, and that it may be possible to reduce the risk associated with these histological risk factors using antiestrogen therapy.

HIN-1, a putative cytokine highly expressed in normal but not cancerous mammary epithelial cells

To identify molecular alterations implicated in the initiating steps of breast tumorogenesis, we compared the gene expression profiles of normal and ductal carcinoma in situ (DCIS) mammary epithelial cells by using serial analysis of gene expression (SAGE). Through the pair-wise comparison of normal and DCIS SAGE libraries, we identified several differentially expressed genes. Here, we report the characterization of one of these genes, HIN-1 (high in normal-1). HIN-1 expression is significantly down regulated in 94% of human breast carcinomas and in 95% of preinvasive lesions, such as ductal and lobular carcinoma in situ. This decrease in HIN-1 expression is accompanied by hypermethylation of its promoter in the majority of breast cancer cell lines (>90%) and primary tumors (74%). HIN-1 is a putative cytokine with no significant homology to known proteins. Reintroduction of HIN-1 into breast cancer cells inhibits cell growth. These results indicate that HIN-1 is a candidate tumor suppressor gene that is inactivated at high frequency in the earliest stages of breast tumorogenesis.

Clinical and pathologic features of breast cancers in women treated for Hodgkin's disease: a case-control study

The goal of this study was to assess whether there are clinical or pathologic differences between radiation-associated breast cancers developing after treatment for Hodgkin's disease and spontaneously arising breast cancers. Clinical and pathologic data were reviewed for 26 Hodgkin's disease patients who received irradiation and subsequently developed breast cancer (cases) and 26 age- and stage-matched patients with sporadic breast cancers (controls). The median age at diagnosis of Hodgkin's disease was 21 years (range 11-40 years), and the median interval between Hodgkin's disease and breast cancer diagnosis was 15 years (range 4-27 years). There were no differences between cases and controls with regard to clinical factors. Cases had a lower frequency of histologic grade III tumors (38% versus 65%, p = 0.09) and moderate to marked mononuclear inflammatory cell reaction (11% versus 35%, p = 0.03). When these covariates were combined, grade III tumors in conjunction with mononuclear inflammatory cell reaction were also seen less frequently in the case group than in the control group (11% versus 31%, p = 0.06). Seven cases developed additional cancers, but no additional cancers developed in the control group (p = 0.01). Patients who developed breast cancers after Hodgkin's disease did not differ from patients with spontaneous breast cancers, with regard to clinical factors. However, the lower frequency of high-grade tumors and moderate to marked mononuclear inflammatory cell reaction among the cases suggests that radiation-associated breast cancers may differ from spontaneously arising cancers in their pathogenesis. Cases appeared to be at increased risk of developing additional cancers, but we cannot exclude surveillance as a possible contributing factor.

Fine-Needle Aspiration Biopsy of Nonpalpable Breast Lesions in a Multicenter Clinical Trial: Results from the Radiologic Diagnostic Oncology Group V

PURPOSE

To determine the diagnostic accuracy of ultrasonographically (US) and stereotactically guided fine-needle aspiration biopsy (FNAB) in the diagnosis of nonpalpable breast lesions.

MATERIALS AND METHODS

At 18 institutions, 442 women who underwent 22-25-gauge imaging-guided FNAB were enrolled. Definitive surgical, core-needle biopsy, and/or follow-up information was available for 423 (95.7%) of these women. The reference standard was established from additional clinical and imaging information for an additional six (1.4%) women who did not undergo further histopathologic evaluation. The FNAB protocol was standardized at all institutions, and all specimens were reread by one of two expert cytopathologists.

RESULTS

When insufficient samples were included in the analysis and classified as positive, the sensitivity and specificity of FNAB were 85%-88% and 55.6%-90.5%, respectively; accuracy ranged from 62.2% to 89.2%. The diagnostic accuracy of FNAB was significantly better for detection of masses than for detection of calcifications (67.3% vs. 53.8%, P =.006) and with US guidance than with stereotactic guidance (77.2% vs. 58.9%; P =.002).

CONCLUSION

FNAB of nonpalpable breast lesions has limited value given the high insufficient sample rate and greater diagnostic accuracy of other interventions, including core-needle biopsy and needle-localized open surgical biopsy.

Quantitative evaluation of HER-2/neu status in breast cancer by fluorescence in situ hybridization and by immunohistochemistry with image analysis

We correlated quantitative results obtained in 40 invasive breast cancer cases for HER-2 gene amplification by fluorescence in situ hybridization with protein expression by immunohistochemical studies with computer-assisted image analysis. Fluorescence in situ hybridization (FISH) results were quantified as the mean number of fluorescent signals per nucleus, and immunohistochemical slides were read by semiquantitatively assessing membranous immunostaining intensity in tumor cells vs nonneoplastic breast tissue or quantitatively evaluated by image analysis. We found high correlation between immunohistochemical results by semiquantitative scoring and by image analysis. FISH results correlated with immunohistochemical results moderately when the staining intensity of only tumor cells was assessed and significantly better when the difference in staining intensity between tumor cells and nonneoplastic breast tissue was assessed. The correlation with FISH results was further improved when immunohistochemical study was combined with heat-induced epitope retrieval (HIER). Although FISH and immunohistochemical studies assess different aspects of the HER-2/neu gene (amplification vs overexpression), we found good correlation between the diagnostic techniques. The correlation was best when immunohistochemical studies were combined with HIER and assessed as the difference between tumor cells and nonneoplastic breast tissue.

Pathologic features of breast cancers in women with previous benign breast disease

To compare pathologic features of the cancers arising after different types of benign breast disease (BBD), we reviewed the invasive breast cancer slides of 169 women with a previous benign biopsy result. Lesions were categorized previously as nonproliferative, proliferative without atypia, or atypical hyperplasia. Pathologic features of the cancers were evaluated without knowledge of the previous BBD category. Estrogen and progesterone receptor immunohistochemistry was performed on available tissue blocks. The median times between a benign result and cancer were 100, 124, and 92 months for women with nonproliferative lesions, proliferative lesions without atypia, and atypical hyperplasia, respectively. Cancers in the 3 groups did not differ significantly in tumor size, axillary lymph node status, or histologic grade, and there was no significant difference in the distribution of histologic types of breast cancer. Lymphatic vessel invasion, extensive intraductal component, and hormone receptor status did not differ among BBD categories. The pathologic features of breast cancers that develop in women with a previous benign biopsy result do not vary according to the histologic category of the previous BBD.

Breast cancer in the 21st century: neu opportunities and neu challenges

Recent advances in the understanding of the molecular and genetic alterations underlying breast cancer development and progression have provided the opportunity to develop novel therapeutic strategies for this disease. None of these developments has had a greater recent impact on clinicians and pathologists than the recognition of the importance of the HER-2/neu (c-erbB-2) oncogene. Located on chromosome 17, this gene encodes a 185 kD transmembrane glycoprotein with tyrosine kinase activity that functions as a growth factor receptor. Amplification or overexpression of HER-2/neu is seen in approximately 20 to 30% of invasive breast cancers and this has been considered to be an adverse prognostic factor in many studies. However, recent interest in HER-2/neu has largely been focused on its role as a potential target for breast cancer treatment. In particular, recognition of the role of HER-2/neu in breast cancer growth led to the development of a humanized monoclonal antibody directed against the HER-2/neu protein as a therapeutic agent (Herceptin). Clinical studies have further suggested that HER-2/neu status can provide important information regarding sensitivity to certain forms of conventional systemic therapy, particularly anthracyclines. As a result of these developments, there has been increasing demand for pathologists to perform assays for HER-2/neu on current and archived breast cancer specimens. Immunohistochemistry and fluorescence in situ hybridization have emerged as the most viable assays for evaluation of HER-2/neu in routine clinical practice. However, each of these methods has its advantages and disadvantages. Determining the relative merits of these assays and developing clinically meaningful and reproducible systems to report the results are challenges pathologists must now address. The development of a therapeutic agent that directly targets a protein involved in a growth-signaling pathway represents a new paradigm in breast cancer treatment. Therapeutic strategies that target other molecules involved in breast cancer development and progression are on the horizon. It is crucial that pathologists become aware of these advances and assume a pivotal role in the development and application of assays to evaluate these new molecular targets.

Carcinomas in situ of the breast with indeterminate features: role of E-cadherin staining in categorization

Most breast carcinomas in situ (CIS) are easily categorized as ductal (DCIS) or lobular (LCIS). However, some CIS have indeterminate histologic features (CIS-IF). Prior studies have shown that E-cadherin protein expression is lost in lobular but not ductal carcinomas. Therefore, evaluation of examples of CIS-IF for E-cadherin expression by immunohistochemistry might be useful in helping to define their nature. To address this, we studied histologic features and E-cadherin expression by immunohistochemistry in 89 cases of breast CIS (28 LCIS, 33 DCIS, 28 CIS-IF). CIS-IF cases were divided into three groups based on histology: Group 1 cases had all the cytologic and architectural features typical of LCIS but showed areas of comedo-type necrosis (n = 6). Group 2 cases were CIS lesions characterized by small, uniform neoplastic cells either growing in a solid pattern with focal microacinar-like structures but with cellular dyshesion, or growing in a cohesive mosaic pattern but with occasional intracytoplasmic vacuoles (n = 17). Group 3 cases showed marked cellular pleomorphism and nuclear atypia but had the dyshesive growth pattern characteristic of LCIS (n = 5). E-cadherin staining was scored as negative, positive, or mixed (mixture of negative and positive tumor cells). All 28 cases of LCIS were E-cadherin negative, and all 33 DCIS cases were E-cadherin positive by immunohistochemistry. All cases from CIS-IF group 1 and group 3 were negative for E-cadherin, suggesting a closer kinship to LCIS than to DCIS. In contrast, CIS-IF group 2 cases were heterogeneous with respect to E-cadherin staining. Six (35.3%) cases were E-cadherin negative (more akin to LCIS), 5 (29.4%) cases were E-cadherin positive (akin to DCIS), and 6 (35.3%) cases had both E-cadherin-positive and E-cadherin-negative tumor cells, suggesting a mixed DCIS/LCIS phenotype. Our findings suggest that E-cadherin immunostaining is of value in helping to characterize breast carcinomas in situ with indeterminate features. However, validation of these observations will require clinical outcome studies.

Diagnostic accuracy of 99mTc-sestamibi breast imaging: multicenter trial results

Although mammography is well established as a first-line tool for breast cancer screening and detection, efforts to develop complementary procedures continue. Observation of 99mTc-sestamibi tumor uptake provided the impetus for its evaluation as an adjunctive technique. This trial's objectives were to determine in a multicenter trial the diagnostic accuracy of 99mTc-sestamibi in women with suspected breast cancer and to investigate factors influencing diagnostic accuracy.

METHODS

Our multicenter trial enrolled 673 women (387 with nonpalpable abnormalities; 286 with palpable abnormalities) scheduled for excisional biopsy or mastectomy. Blinded and unblinded interpretations of scintigraphic images were compared with core laboratory established histopathologic diagnoses to define the diagnostic accuracy of 99mTc-sestamibi breast imaging.

RESULTS

Blinded readers' diagnostic accuracy was 78%-81%. Inter-reader agreement was excellent, ranging from 95% to 100% (kappa = 0.82-0.99). Overall institutional sensitivity and specificity for 99mTc-sestamibi breast imaging were 75.4% and 82.7%, respectively. In this population with a 40.1% disease prevalence, the positive predictive value was 74.5% and the negative predictive value was 83.4%. The negative predictive value was 94% in patients with a 40% or lower mammographic likelihood of breast cancer. Sensitivity was higher for palpable abnormalities; specificity was higher for nonpalpable abnormalities. Sensitivity was decreased for tumors <1 cm in largest dimension but appeared not to be affected by patient's age.

CONCLUSION

As an adjunct to current procedures, 99mTc-sestamibi breast imaging may contribute to patient management decisions in selected populations, including women with dense breasts, mammographically indeterminate lesions >1 cm, and palpable abnormalities.

Biopsy confirmed benign breast disease, postmenopausal use of exogenous female hormones, and breast carcinoma risk

BACKGROUND

A history of proliferative benign breast disease has been shown to increase the risk of developing breast carcinoma, but, to the authors' knowledge, how postmenopausal exogenous female hormone use, in general, has affected breast carcinoma risk among women with a history of proliferative breast disease with or without atypia has not been well established.

METHODS

In the current case-control study, nested within the Nurses' Health Study, benign breast biopsy slides of 133 postmenopausal breast carcinoma cases and 610 controls with a history of benign breast disease, were reviewed. Reviewers had no knowledge of case status.

RESULTS

Women with proliferative disease without atypia had a relative risk for postmenopausal breast carcinoma of 1.8 (95%, confidence interval [CI]: 1.1 to 2.8), and women with atypical hyperplasia had a relative risk of 3.6 (95%, CI: 2.0 to 6.4) compared with women who had nonproliferative benign histology. Neither current postmenopausal use of exogenous female hormones nor long term use for 5 or more years further increased the risk of breast carcinoma in the study population beyond that already associated with their benign histology.

CONCLUSIONS

Women who had proliferative benign breast disease, with or without atypia, were at moderately to substantially increased risk of developing postmenopausal breast carcinoma compared with women who had nonproliferative benign conditions. In the current study, postmenopausal exogenous female hormone use in general did not further increase the breast carcinoma risk for women with proliferative benign breast disease. However, the analysis did not exclude the possibility of increased risk with a particular hormone combination or dosage.

Is radiation alone adequate treatment to the axilla for patients with limited axillary surgery? Implications for treatment after a positive sentinel node biopsy

PURPOSE

To estimate the possible efficacy of axillary radiation therapy (AXRT) following a positive sentinel node biopsy (SNB), we evaluated the risk of regional nodal failure (RNF) for patients with clinical Stage I or II, clinically node-negative invasive breast cancer treated with either no dissection or a limited dissection (LD) defined as removal of 5 nodes or less followed by AXRT.

MATERIALS AND METHODS

From 1978 to 1987, 292 patients underwent AXRT in the absence of axillary dissection; 126 underwent AXRT following LD. The median dose to the axilla was 46 Gy. The median dose to the supraclavicular fossa was 45 Gy. Among patients found to have positive nodes on LD, adjuvant chemotherapy and tamoxifen were administered to 81% and 7% of subjects, respectively. All patients had potential 8-year follow-up.

RESULTS

Six of the 418 patients (1. 4%) developed RNF as a first site of failure within 8 years. Among these 6 patients (1.4%) with RNF as the first site of failure, 4 had simultaneous distant and regional recurrences; and 2 had isolated axillary failures. Three of the 292 patients (1%) with no axillary dissection, none of 84 patients with pathologically negative nodes and 3 of 42 patients (7%) with pathologically involved nodes had RNF as a first site of failure. Radiation pneumonitis developed in 5 patients (1.2%), brachial plexopathy in 5 (1.2%) and arm edema in 4 (1.2%). In all cases, radiation pneumonitis and brachial plexopathy were transient.

CONCLUSION

These results imply that AXRT may be an effective and safe alternative to completion dissection for treatment of the axilla following a positive SNB. Further studies comparing these two options in specific patient subgroups are needed.

The relationship between lymphatic vessell invasion, tumor size, and pathologic nodal status: can we predict who can avoid a third field in the absence of axillary dissection?

PURPOSE

Tangential (2-field) radiation therapy to the breast and lower axilla is typically used in our institution for treating patients with early-stage breast cancer who have 0-3 positive axillary nodes, as determined by axillary dissection, whereas a third supraclavicular/axillary field is added for patients with 4 or more positive nodes. However, dissection may result in complications and added expense. We, therefore, assessed whether clinical or pathologic factors of the primary tumor could reliably predict, in the absence of an axillary dissection, which patients with clinically negative axillary nodes have such limited pathologic nodal involvement that they might be effectively treated with only tangential fields. This would eliminate both the complications of axillary dissection and the added complexity and potential morbidity of a supraclavicular/axillary field.

METHODS AND MATERIALS

In this study, 722 women with clinical Stage I or II unilateral invasive breast cancer of infiltrating ductal histology, with clinically negative axillary nodes, at least 6 lymph nodes recovered on axillary dissection, and central pathology review were treated with breast-conserving therapy from 1968 to 1987. Pathologic nodal status was assessed in relation to clinical T stage, the presence of lymphatic vessel invasion (LVI), age, histologic grade, and the location of the primary tumor.

RESULTS

LVI, T stage, and tumor location were each significantly correlated with nodal status on univariate analysis. Ninety-seven percent of LVI-negative patients had 0-3 positive axillary nodes compared to 87% of LVI-positive patients. There was no association between T stage and extent of axillary involvement within LVI-negative and LVI-positive subgroups. In a logistic regression model, only LVI remained a significant predictor of having 4 or more positive nodes, although tumor size was of borderline significance. The odds ratio for LVI (positive vs. negative) as a predictor of having 4 or more positive nodes was 3.9 (95% CI, 2.0-7.6).

CONCLUSION

For patients with clinical T1-2, N0, infiltrating ductal carcinomas, the presence of LVI is predictive of having 4 or more positive axillary nodes. Only 3% of patients with clinical T1-2, N0, LVI-negative breast cancers had 4 or more positive nodes on axillary dissection. Such patients may be reasonable candidates for treatment with tangential radiation fields in the absence of axillary dissection.

Prognostic factors in breast cancer. College of American Pathologists Consensus Statement 1999

BACKGROUND

Under the auspices of the College of American Pathologists, a multidisciplinary group of clinicians, pathologists, and statisticians considered prognostic and predictive factors in breast cancer and stratified them into categories reflecting the strength of published evidence.

MATERIALS AND METHODS

Factors were ranked according to previously established College of American Pathologists categorical rankings: category I, factors proven to be of prognostic import and useful in clinical patient management; category II, factors that had been extensively studied biologically and clinically, but whose import remains to be validated in statistically robust studies; and category III, all other factors not sufficiently studied to demonstrate their prognostic value. Factors in categories I and II were considered with respect to variations in methods of analysis, interpretation of findings, reporting of data, and statistical evaluation. For each factor, detailed recommendations for improvement were made. Recommendations were based on the following aims: (1) increasing uniformity and completeness of pathologic evaluation of tumor specimens, (2) enhancing the quality of data collected about existing prognostic factors, and (3) improving patient care.

RESULTS AND CONCLUSIONS

Factors ranked in category I included TNM staging information, histologic grade, histologic type, mitotic figure counts, and hormone receptor status. Category II factors included c-erbB-2 (Her2-neu), proliferation markers, lymphatic and vascular channel invasion, and p53. Factors in category III included DNA ploidy analysis, microvessel density, epidermal growth factor receptor, transforming growth factor-alpha, bcl-2, pS2, and cathepsin D. This report constitutes a detailed outline of the findings and recommendations of the consensus conference group, organized according to structural guidelines as defined.

Outcome at 8 years after breast-conserving surgery and radiation therapy for invasive breast cancer: influence of margin status and systemic therapy on local recurrence

PURPOSE

To examine the relationship between pathologic margin status and outcome at 8 years after breast-conserving surgery and radiation therapy.

PATIENTS AND METHODS

The study population comprised 533 patients with International Union Against Cancer/American Joint Committee on Cancer clinical stage I or II breast cancer who had assessable margins, who received at least 60 Gy to the primary tumor bed, and who had more than 8 years of potential follow-up. Each margin was scored (according to the presence of invasive or in situ disease that touched the inked surgical margin) as one of the following: negative, close, focally positive, or extensively positive. Outcome at 8 years was calculated using crude rates of first site of failure. A polychotomous logistic regression analysis was performed. Median follow-up time was 127 months.

RESULTS

At 8 years, patients with close margins and those with negative margins both had a rate of local recurrence (LR) of 7%. Patients with extensively positive margins had an LR rate of 27%, whereas patients with focally positive margins had an intermediate rate of LR of 14%. In the polychotomous logistic regression model, margin status and the use of systemic therapy were the only two variables that had significant effects on the risk ratio of LR to remaining alive and free of disease. Among the 45 patients with focally positive margins who received systemic therapy, the crude LR rate was 7% at 8 years (95% confidence interval, 1% to 20%).

CONCLUSION

Pathologic margin status and the use of adjuvant systemic therapy are the most important factors associated with LR among patients treated with breast-conserving surgery and radiation therapy.

The relation between the presence and extent of lobular carcinoma in situ and the risk of local recurrence for patients with infiltrating carcinoma of the breast treated with conservative surgery and radiation therapy

BACKGROUND

When found in an otherwise benign biopsy, lobular carcinoma in situ (LCIS) has been associated with an increased risk of development of a subsequent invasive breast carcinoma. However, the association between LCIS and the risk of subsequent local recurrence in patients with infiltrating carcinoma treated with conservative surgery and radiation therapy has received relatively little attention.

METHODS

Between 1968 and 1986, 1625 patients with clinical Stage I-II invasive breast carcinoma were treated at the Joint Center for Radiation Therapy at Harvard Medical School with breast-conserving surgery (CS) and radiation therapy (RT) to a total dose to the primary site of > or =60 grays. Analysis was limited to 1181 patients with infiltrating ductal carcinoma, infiltrating lobular carcinoma, or infiltrating carcinoma with mixed ductal and lobular features who, on review of their histologic slides, had sufficient normal tissue adjacent to the tumor to evaluate for the presence of LCIS and also had a minimum potential follow-up time of 8 years. The median follow-up time was 161 months.

RESULTS

One hundred thirty-seven patients (12%) had LCIS either within the tumor or in the macroscopically normal adjacent tissue. The 8-year crude risk of recurrence was not significantly increased for patients with LCIS associated with invasive ductal, invasive lobular, or mixed ductal and lobular carcinoma. Among the 119 patients with associated LCIS adjacent to the tumor, the 8-year rate of local recurrence was 13%, compared with 12% for the 1062 patients without associated LCIS. For the 70 patients with moderate or marked LCIS adjacent to the tumor, the 8-year rate of local recurrence was 13%. The extent of LCIS did not affect the risk of recurrence. The risks of contralateral disease and of distant failure were similarly not affected by the presence or extent of LCIS.

CONCLUSIONS

Breast-conserving therapy involving limited surgery and radiation therapy is an appropriate method of treating patients with invasive breast carcinoma with or without associated LCIS. Neither the presence nor the extent of LCIS should influence management decisions regarding patients with invasive breast carcinoma. [See editorial counterpoint and reply to counterpoint on pages 978-81 and 982-3, this issue.]

HER-2/neu protein expression in breast cancer evaluated by immunohistochemistry. A study of interlaboratory agreement

Immunohistochemistry (IHC) is used commonly for evaluating HER-2/neu protein expression in breast cancer. Given the potential clinical importance of HER-2/neu status in patient management, interlaboratory variability in HER-2/neu IHC results in a matter of legitimate concern. We compared the results from 2 laboratories for HER-2/neu determined by IHC on paraffin sections of the same 100 consecutive invasive breast cancers. Both laboratories used the same primary antibody; however, different methods for heat-induced epitope retrieval (microwave or steam) and immunostaining (automated equipment from different manufacturers) and different scoring systems (positive-negative and 0-4+) were used. Slides were read in a blinded fashion and the results from the 2 laboratories were compared. Of the 93 cases evaluable in both laboratories, 24% were scored as HER-2/neu-positive at 1 laboratory, and 23% were scored as positive at the other. Complete concordance in categorization of HER-2/neu status between the 2 laboratories was achieved in 90 of 93 cases. Excellent interlaboratory agreement for HER-2/neu IHC was attained using the same primary antibody to HER-2/neu, even without standardization of assay method or scoring criteria. However, standardization of these parameters remains an important objective to optimize interlaboratory agreement.

The influence of infiltrating lobular carcinoma on the outcome of patients treated with breast-conserving surgery and radiation therapy

BACKGROUND

The role of conservative surgery and radiation therapy (CS and RT) in the treatment of patients with infiltrating ductal carcinoma is well established. However, the efficacy of CS and RT for patients with infiltrating lobular carcinoma is less well documented. The goal of this study was to examine treatment outcome after CS and RT for patients with infiltrating lobular carcinoma and to compare the results to those of patients with infiltrating ductal carcinoma and patients with mixed ductal-lobular histology.

METHODS

Between 1970 and 1986, 1624 patients with Stage I or II invasive breast cancer were treated with CS and RT consisting of a complete gross excision of the tumor and > or = 6000 cGy to the primary site. Slides were available for review for 1337 of these patients (82%). Of these, 93 had infiltrating lobular carcinoma, 1089 had infiltrating ductal carcinoma, and 59 had tumors with mixed ductal and lobular features; these patients constitute the study population. The median follow-up time for surviving patients was 133 months. A comprehensive list of clinical and pathologic features was evaluated for all patients. Additional histologic features assessed for patients with infiltrating lobular carcinoma included histologic subtype, multifocal invasion, stromal desmoplasia, and the presence of signet ring cells.

RESULTS

Five and 10-year crude results by site of first failure were similar for patients with infiltrating lobular, infiltrating ductal, and mixed histology. In particular, the 10-year crude local recurrence rates were 15%, 13%, and 13% for patients with infiltrating lobular, infiltrating ductal, and mixed histology, respectively. Ten-year distant/regional recurrence rates were 22%, 23%, and 20% for the three groups, respectively. In addition, the 10-year crude contralateral breast cancer rates were 4%, 13% and 6% for patients with infiltrating lobular, infiltrating ductal and mixed histology, respectively. In a multiple regression analysis which included established prognostic factors, histologic type was not significantly associated with either survival or time to recurrence.

CONCLUSIONS

Patients with infiltrating lobular carcinoma have a similar outcome following CS and RT to patients with infiltrating ductal carcinoma and to patients with tumors that have mixed ductal and lobular features. We conclude that the presence of infiltrating lobular histology should not influence decisions regarding local therapy in patients with Stage I and II breast cancer.

The significance of extracapsular extension of axillary lymph node metastases in early-stage breast cancer

PURPOSE

To investigate if extracapsular extension (ECE) of axillary lymph node metastases predicts for a decreased rate of disease-free survival or an increased rate of regional recurrence of breast carcinoma.

METHODS

The study population consisted of 368 patients with T1 or T2 breast cancer and pathologically-positive lymph nodes treated with breast-conserving therapy between 1968 and 1986. The median number of sampled lymph nodes was 10. Median follow-up time for the surviving patients was 139 months (range 70-244). Twenty percent of the patients were treated with supraclavicular RT, and 64% received both axillary and supraclavicular RT, with a median dose to the nodes of 45 Gy. The following factors were evaluated: presence of ECE, number of sampled lymph nodes (LN), number of involved LN, size of primary tumor, histologic grade of tumor, presence of lymphatic vessel invasion (LVI), presence of an extensive intraductal component (EIC), radiation dose, use of adjuvant chemotherapy, and age of patient. Recurrences were reported as the 5-year crude sites of first failure, and were divided into breast recurrences (LR), regional nodal failure (RNF, defined as isolated axillary, supraclavicular, or internal mammary recurrence), and distant metastases (DM).

RESULTS

One hundred twenty-two patients (33%) had ECE and 246 patients did not. The median number of LN with ECE was 1 (range 1-10) and 20% of patients had ECE in > or =4 LN. Patients with ECE tended to be older (median age 51 vs. 47, p = 0.01), and had a higher number of involved LN (median 3 vs. 2, p = 0.005) than patients without ECE. Forty-three percent of patients with ECE had > or =4 involved LN compared to 15% of patients without ECE (p<0.0001). Models of ECE and the above factors revealed no significant correlation between ECE and either disease-free or overall survival. There was no statistically significant increase in local, regional nodal, or distant failures in patients with ECE as compared to patients without ECE.

CONCLUSION

In this population of patients with nodal involvement, the presence of ECE correlates with the number of involved LN but does not appear to add predictive power to models of local, regional, or distant recurrence when the number of positive LN is included.

Factors associated with regional nodal failure in patients with early stage breast cancer with 0-3 positive axillary nodes following tangential irradiation alone

PURPOSE

Recent randomized trials have suggested that improved local-regional control after radiation therapy significantly increases survival for breast cancer patients with positive axillary nodes treated with adjuvant systemic therapy (1, 2). It has been our policy to use a third radiation field only in patients with 4 or more positive nodes. The purpose of this study was to assess whether there are any clinical or pathologic factors associated with an increased risk of regional nodal failure (RNF) in patients with 0-3 positive nodes treated with tangential radiotherapy (RT) alone with or without systemic therapy.

METHODS AND MATERIALS

We retrospectively analyzed the incidence of RNF for 691 patients with clinical Stage I or II invasive breast cancer treated with complete gross excision of the primary tumor and tangential RT alone between 1978-87; 12% also received systemic therapy. All had 0-3 positive nodes on axillary dissection that had histologic examination of > or =6 nodes, and all had potential 8-year follow-up. The median number of axillary nodes removed was 11 (range 6-36). RNF was defined as any recurrence in ipsilateral axillary, internal mammary, supraclavicular, or infraclavicular nodes in the absence of recurrence in the breast, with or without simultaneous distant metastasis. Crude rates for first sites of failure within the first 8 years after treatment were calculated. A polychotomous logistic regression was used to identify factors prognostic for RNF and other sites of first failure.

RESULTS

Within 8 years, RNF was the first site of failure for 27 patients for a crude 8-year rate of 3.9%. Isolated axillary failure occurred in 8 patients (1.2%). Isolated supraclavicular and/or infraclavicular failure occurred in 5 (1.3%) and 3 (0.4%) patients, respectively. Isolated internal mammary node failure occurred in 2 patients (0.3%). A polychotomous logistic regression model of first site of failure (local failure, regional nodal, distant/ opposite breast, dead without recurrence, no evidence of disease) within 8 years found age <50 years, moderate or marked necrosis, size greater than 1 cm, and presence of an extensive intraductal component (EIC) to be significantly correlated with site of first failure, but only the last two were associated with a significantly larger relative risk of RNF versus being no evidence of disease at 8 years. The incidence of RNF was 0.7% for patients with tumors < or =1 cm compared to 5.7% among patients with larger tumors. Among patients with EIC-positive tumors the incidence of RNF was 7.6% compared to 3.1% among those whose tumors were EIC-negative.

CONCLUSIONS

Although the incidence of RNF has been shown to be somewhat higher in patients with tumors measuring greater than 1 cm and those with an EIC, RNF is uncommon among all subsets of patients with negative or 1-3 positive lymph nodes treated with conservative surgery, axillary dissection, and only tangential RT fields. Therefore, giving only tangential RT (without a separate nodal field) appears generally acceptable for patients with 0-3 positive nodes.

Association of age and reproductive factors with benign breast tissue composition

Reproductive breast cancer risk factors are hypothesized to act by increasing exposure of the breast to endogenous estrogens, but few studies have quantitatively examined the association of these risk factors with breast tissue composition. This study is part of a case-control study of breast histological characteristics and breast cancer risk, nested within the Nurses' Health Study, a prospective study of 121,700 registered nurses. We studied 300 women who had not been diagnosed with breast cancer, but for whom we obtained slides from a prior benign breast biopsy. We used a computer-assisted image analysis technique to assess the proportion of epithelial and fibrous stromal tissue on benign breast biopsy slides, excluding obvious mass lesions. Mean epithelial proportion was 5.3% (0.1-23%), and mean stromal proportion was 58.7% (3-93%). Women with proliferative breast disease without atypia had higher epithelial and stromal proportions than women with nonproliferative breast disease (P < 0.001). Postmenopausal women had a lower epithelial proportion (P = 0.01), and increasing age at biopsy was associated with decreasing stromal proportion among postmenopausal parous women (P = 0.004). Among premenopausal women, increasing years since last birth was associated with lower epithelial proportion (P < 0.001). Other reproductive risk factors were not independently associated with epithelial or stromal proportion. Epithelial and stromal breast tissue were associated with different factors with the exception of proliferative breast disease, which was associated with an increase in both epithelial and stromal proportion. The quantitative measurement of epithelial and stromal proportion may be useful for measuring changes in breast composition.

Assessment of pathologic prognostic factors in breast core needle biopsies

BACKGROUND

Core needle biopsies (CNB) are being used increasingly as the initial diagnostic procedure in women with breast cancer. Many clinicians are interested in obtaining as much prognostic information as possible from these limited specimens. However, the accuracy of assessing pathologic prognostic factors in core biopsy material has not been studied in detail.

DESIGN

We studied CNB and subsequent excision specimens from 79 women with invasive breast cancer. Slides from CNB and excision specimens were reviewed in a blinded fashion and each was assessed for histologic type, tumor size, histologic grade, lymphatic vessel invasion (LVI), and the presence of an extensive intraductal component (EIC).

RESULTS

Among the 79 cancers, there were 58 invasive ductal carcinomas, six invasive lobular carcinomas, 13 invasive carcinomas with ductal and lobular features and two tubular carcinomas, based on examination of the excision specimens. Histologic type on CNB correlated with that on excision in 64 cases (81%). Although there was a significant correlation between tumor size on CNB and excision specimens (r2 = 0.30, P = 0.01), the pathologic T stage was underestimated on CNB in 79% of cases. Furthermore, T substage was underestimated on CNB in 71% of T1 lesions. There was concordance in histologic grade between CNB and excisions in 75% of cases. Among the 20 discordant cases, the grade was higher in the excision than in the CNB in 13 cases and lower in seven. However, all discrepancies were within one grade. None of the 17 cancers with LVI in the excision specimen showed LVI on the CNB. Among 14 cases with an EIC on the excision specimen, only four (29%) were scored as having an EIC on CNB.

CONCLUSION

Histologic type can be accurately determined on CNB in most cases. While there was concordance in histologic grade between CNB and excision in the majority of cases, grade was discordant in a substantial minority (25%). The ability to accurately determine tumor size (pathologic T-stage), LVI, and EIC on CNB is severely limited.

Lobular carcinoma in situ: current concepts and controversies

Clinical and clinicopathologic studies performed over the last 50 years have elucidated many of the important features of lobular carcinoma in situ. However, certain aspects of the natural history, treatment, and diagnosis of these lesions remain controversial. The purpose of this article is to review the current understanding of lobular carcinoma in situ and to highlight some of the controversies surrounding this entity.

Comparison of fluorescence in situ hybridization and immunohistochemistry for the evaluation of HER-2/neu in breast cancer

PURPOSE

To compare fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in the determination of HER-2/neu status of breast cancers.

MATERIALS AND METHODS

FISH and IHC for HER-2/neu were performed on formalin-fixed paraffin sections of 100 consecutive invasive breast cancers. FISH was performed at Beth Israel Deaconess Medical Center, Boston, MA, using the Oncor/Ventana INFORM kit (Ventana Medical Systems, Tucson, AZ; formerly sold by Oncor, Inc, Gaithersburg, MD) in a laboratory certified as proficient in this procedure. IHC was performed at PhenoPath Laboratories, Seattle, WA, using a polyclonal antibody to the HER-2/neu protein. FISH and IHC were analyzed in a blinded fashion, and the results were then compared. Procedure and interpretation times and reagent costs for FISH and IHC were also compared.

RESULTS

HER-2/neu was amplified by FISH in 26% of cases, and 23% were HER-2/neu-positive by IHC. FISH and IHC were both assessable in 90 cases. Concordance between FISH and IHC results was seen in 82 of these cases (91%, P <.001). The FISH procedure required more technologist time and more interpretation time per case for the pathologist than IHC. Reagent costs were substantially higher for FISH than for IHC.

CONCLUSION

There is a high level of correlation between FISH and IHC in the evaluation of HER-2/neu status of breast cancers using formalin-fixed paraffin-embedded specimens. Although the choice of which assay to use should be left for individual laboratories to make based on technical and economic considerations, our results may make it difficult to justify the routine use of FISH for determination of HER-2/neu status in breast cancer.

Specificity of HercepTest in determining HER-2/neu status of breast cancers using the United States Food and Drug Administration-approved scoring system

PURPOSE

To evaluate the specificity of the HercepTest for Immunoenzymatic Staining (Dako Corp, Carpinteria, CA) for determining HER-2/neu protein expression in breast cancer.

MATERIALS AND METHODS

Forty-eight invasive breast cancers previously found to be HER-2/neu-negative by two different immunohistochemical (IHC) assays and not amplified for the HER-2/neu gene by fluorescence in situ hybridization were studied using the HercepTest kit. HercepTest was performed according to the manufacturer's guidelines, and the results were scored on a 0 to 3+ scale using the United States Food and Drug Administration (FDA)-approved grading system. In this system, cases scored as 2+ or 3+ are considered HER-2/neu-positive.

RESULTS

Among these 48 cases, the IHC score using the FDA-approved scoring system was 0 in four cases (8.3%), 1+ in 16 (33.3%), 2+ in 21 (43.8%), and 3+ in seven (14.6%). Therefore, 58.4% of these cases were categorized as HER-2/neu-positive, and the specificity of the HercepTest kit for HER-2/neu expression was 41.6%. However, with the use of a modified scoring system that took into account the level of staining of nonneoplastic epithelium, the specificity increased to 93.2%.

CONCLUSION

Our results indicate that the HercepTest kit, when used in accordance with the manufacturer's guidelines and the FDA-approved scoring system, results in a large proportion of breast cancers being categorized as positive for HER-2/neu protein expression and that many of these seem to be false-positives. Consideration of the level of staining of nonneoplastic epithelium resulted in improved specificity. The current FDA-approved scoring system for HercepTest results should be reevaluated before its widespread use in clinical practice.