Distant disease-free interval, site of first relapse and post-relapse survival in BRCA1- and BRCA2-associated compared to sporadic breast cancer patients

Breast cancers arising in subjects with germline BRCA1 or BRCA2 mutations: Different biological and clinical entities with potentially diverse therapeutic opportunities

Breast cancers (BCs) arising in carriers of germline BRCA1 and BRCA2 pathogenic variants (PVs) have long been considered as indistinguishable biological and clinical entities. However, the loss of function of BRCA1 or BRCA2 proteins has different consequences in terms of tumor cell reliance on estrogen receptor signaling and tumor microenvironment composition. Here, we review accumulating preclinical and clinical data indicating that BRCA1 or BRCA2 inactivation may differentially affect BC sensitivity to standard systemic therapies. Based on a different crosstalk between BRCA1 or BRCA2 and the ER pathway, BRCA2-mutated Hormone Receptor-positive, HER2-negative advanced BC may be less sensitive to endocrine therapy (ET) plus CDK 4/6 inhibitors (CDK 4/6i), whereas BRCA2-mutated triple-negative breast cancer (TNBC) may be especially sensitive to immune checkpoint inhibitors. If validated in future prospective studies, these data may have relevant clinical implications, thus establishing different treatment paths in patients with BRCA1 or BRCA2 PVs.

Bone serves as a transfer station for secondary dissemination of breast cancer

Metastasis is responsible for the majority of deaths among breast cancer patients. Although parallel polyclonal seeding has been shown to contribute to organ-specific metastasis, in the past decade, horizontal cross-metastatic seeding (metastasis-to-metastasis spreading) has also been demonstrated as a pattern of distant metastasis to multiple sites. Bone, as the most frequent first destination of breast cancer metastasis, has been demonstrated to facilitate the secondary dissemination of breast cancer cells. In this review, we summarize the clinical and experimental evidence that bone is a transfer station for the secondary dissemination of breast cancer. We also discuss the regulatory mechanisms of the bone microenvironment in secondary seeding of breast cancer, focusing on stemness regulation, quiescence-proliferation equilibrium regulation, epigenetic reprogramming and immune escape of cancer cells. Furthermore, we highlight future research perspectives and strategies for preventing secondary dissemination from bone.

New challenges in integrated diagnosis by imaging and osteo-immunology in bone lesions

INTRODUCTION

High-resolution imaging is the gold standard to measure the functional and biological features of bone lesions. Imaging markers have allowed the characterization both of tumour heterogeneity and metabolic data. Besides, ongoing studies are evaluating a combined use of 'imaging markers', such as SUVs, MATV, TLG, ADC from PET and MRI techniques respectively, and several 'biomarkers' spanning from chemokine immune-modulators, such as PD-1, RANK/RANKL, CXCR4/CXCL12 to transcription factors, such as TP53, RB1, MDM2, RUNX family, EZH2, YY1, MAD2. Osteoimmunology may improve diagnosis and prognosis leading to precision medicine in bone lesion treatment. Areas covered: We investigated modalities (molecular and imaging approach) useful to identify bone lesions deriving both from primary bone tumours and from osteotropic tumours, which have a higher incidence, prevalence and prognosis. Here, we summarized the recent advances in imaging techniques and osteoimmunology biomarkers which could play a pivotal role in personalized treatment. Expert commentary: Although imaging and molecular integration could allow both early diagnosis and stratification of cancer prognosis, large scale clinical trials will be necessary to translate pilot studies in the current clinical setting.

ABBREVIATIONS

ADC: apparent diffusion coefficient; ALCAM: Activated Leukocyte Cell Adhesion Molecule; ALP: Alkaline phosphatases; BC: Breast cancer; BSAP: B-Cell Lineage Specific Activator; BSAP: bone-specific alkaline phosphatase; BSP: bone sialoprotein; CRIP1: cysteine-rich intestinal protein 1; CD44: cluster of differentiation 44; CT: computed tomography; CXCL12: C-X-C motif ligand 12; CXCR4: C-X-C C-X-C chemokine receptor type 4; CTLA-4: Cytotoxic T-lymphocyte antigen 4; CTX-1: C-terminal end of the telopeptide of type I collagen; DC: dendritic cell; DWI: Diffusion-weighted MR image; EMT: mesenchymal transition; ET-1: endothelin-1; FDA: Food and Drug Administration; FDG: ¹⁸F-2-fluoro-2-deoxy-D-glucose; FGF: fibroblast growth factor; FOXC2: forkhead box protein C2: HK-2: hexokinase-2; ICTP: carboxyterminal cross-linked telopeptide of type I collagen; IGF-1R: Insulin Like Growth Factor 1 Receptor; ILC: innate lymphocytes cells; LC: lung cancer; IL-1: interleukin-1; LYVE1: lymphatic vessel endothelial hyaluronic acid receptor 1; MAD2: mitotic arrest deficient 2; MATV: metabolically active tumour volume; M-CSF: macrophage colony stimulating factor; MM: multiple myeloma; MIP1a: macrophage inflammatory protein 1a; MSC: mesenchymal stem cell; MRI: magnetic resonance imaging; PC: prostate cancer; NRP2: neuropilin 2; OPG: osteoprotogerin; PDGF: platelet-derived growth factor; PD-1: Programmed Cell Death 1; PET: positron emission tomography; PINP: procollagen type I N propeptide; PROX1: prospero homeobox protein 1; PSA: Prostate-specific antigen; PTH: parathyroid hormone; RANK: Receptor activator of NF-kB ligand; RECK: Reversion-inducing-cysteine-rich protein; SEMAs: semaphorins; SPECT: single photon computed tomography; SUV: standard uptake value; TLG: total lesion glycolysis; TP53: tumour protein 53; VCAM-1: vascular endothelial molecule-1; VOI: volume of interest; YY1: Yin Yang 1.

Molecular determination of the clonal relationships between multiple tumors in BRCA1/2-associated breast and/or ovarian cancer patients is clinically relevant

Female BRCA1/2 mutation carriers affected with breast and/or ovarian cancer may develop new tumor deposits over time. It is of utmost importance to know the clonal relationships between multiple tumor localizations, enabling differentiation between multiple primaries or metastatic disease with consequences for therapy and prognosis. We evaluated the value of targeted next generation sequencing in the diagnostic workup of BRCA1/2 mutation carriers with ≥2 tumor localizations and uncertain tumor origins. Forty-two female BRCA1/2 mutation carriers with ≥2 tumor localizations were selected. Patients with inconclusive tumor origin after histopathological revision were 'cases'; patients with certain tumor origin of ≥3 tumors served as 'controls'. Tumors of cases and controls were analyzed by targeted next generation sequencing using a panel including CDKN2A, PTEN and TP53, hotspot mutation sites for 27 different genes and 143 single nucleotide polymorphisms for detection of loss of heterozygosity. Based on prevalence of identical or different mutations and/or loss of heterozygosity patterns, tumors were classified as 'multiple primaries' or 'one entity'. Conventional histopathology yielded a conclusive result in 38/42 (90%) of patients. Four cases and 10 controls were analyzed by next generation sequencing. In 44 tumor samples, 48 mutations were found; 39 (81%) concerned TP53 mutations. In all 4 cases, the intra-patient clonal relationships between the tumor localizations could be unequivocally identified by molecular analysis. In all controls, molecular outcomes matched the conventional histopathological results. In most BRCA1/2 mutation carriers with multiple tumors routine pathology work-up is sufficient to determine tumor origins and relatedness. In case of inconclusive conventional pathology results, molecular analyses using next generation sequencing can reliably determine clonal relationships between tumors, enabling optimal treatment of individual patients.

BRCA mutation genetic testing implications in the United States

BRCA mutation carriers have a very high risk of breast and ovarian cancer by age 70, in the ranges 47%-66% and 40%-57%, respectively. Additionally, women with BRCA mutation-associated breast cancer also have an elevated risk of other or secondary malignancies. Fortunately, the breast and ovarian cancer outcome for BRCA1/2 mutation carriers is at least as good as for non-carriers with chemoprevention, prophylactic surgeries and appropriate use of therapies. Therefore, identification of those who might have a mutation is important so that genetic counseling, testing, screening and prevention strategies can be applied in a timely manner. This article reviews the impact of genetic testing in general, timing of genetic testing after diagnosis and prior knowledge of mutation status in BRCA carriers with newly diagnosed breast cancer. Additionally, risk-reducing surgeries including the prophylactic contralateral mastectomy, and bilateral salpingo-oophorectomy and the sensitivity of BRCA-defective breast cancer cell lines to differential chemotherapeutic agents will be discussed.

Survival benefit in women with BRCA1 mutation or familial risk in the MRI screening study (MRISC)

Adding MRI to annual mammography screening improves early breast cancer detection in women with familial risk or BRCA1/2 mutation, but breast cancer specific metastasis free survival (MFS) remains unknown. We compared MFS of patients from the largest prospective MRI Screening Study (MRISC) with 1:1 matched controls. Controls, unscreened if<50 years, and screened with biennial mammography if ≥50 years, were matched on risk category (BRCA1, BRCA2, familial risk), year and age of diagnosis. Of 2,308 MRISC participants, breast cancer was detected in 93 (97 breast cancers), who received MRI <2 years before breast cancer diagnosis; 33 BRCA1 mutation carriers, 18 BRCA2 mutation carriers, and 42 with familial risk. MRISC patients had smaller (87% vs. 52% <T2, p < 0.001), more often node negative (69% vs. 44%, p = 0.001) tumors and received less chemotherapy (39% vs. 77%, p < 0.001) and hormonal therapy (14% vs. 47%, p < 0.001) than controls. Median follow-up time was 9 years (range 0-14). Breast cancer metastasized in 9% (8/93) of MRISC patients and in 23% (21/93) of controls (p = 0.009). MFS was better in MRISC patients overall (log-rank p = 0.008, HR 0.36, 95% CI 0.16-0.80), with familial risk (log-rank p = 0.024, HR: 0.21, 95% CI 0.04-0.95), and in BRCA1 mutation carriers (log-rank p = 0.055, HR 0.30, 95% CI 0.08-1.13). MFS remained better in MRISC patients after lead time correction (log-rank p = 0.020, HR 0.40, 95% CI 0.18-0.90). Overall survival was non-significantly better in MRISC patients (log-rank p = 0.064, HR 0.51, CI 0.24-1.06). Annual screening with MRI and mammography improves metastasis free survival in women with BRCA1 mutation or familial predisposition.

Breast cancer subtypes predispose the site of distant metastases

OBJECTIVES

The distant organs to which breast cancer preferentially metastasizes are of significant clinical importance.

METHODS

We explored the relationship between the clinicopathologic factors and the common sites of distant metastasis in 531 consecutive patients with advanced breast cancer.

RESULTS

Breast cancer subtype as a variable was significantly associated with all five common sites of relapse by multivariate analysis. The luminal tumors were remarkable for their significant bone-seeking phenotype and were less frequently observed in lung, brain, and pleural metastases and less likely to be associated with multiorgan relapse. The HER2 subtype demonstrated a significant liver-homing characteristic. African Americans were significantly less likely to have brain-only metastasis in patients with brain relapse.

CONCLUSIONS

These findings further articulate that breast cancer subtypes differ not only in tumor characteristics but also in their metastatic behavior, thus raising the possibility that this knowledge could potentially be used in determining the appropriate strategy for follow-up of patients with newly diagnosed breast cancer.

Circulating and disseminated tumor cells from breast cancer patient-derived xenograft-bearing mice as a novel model to study metastasis

Introduction

Real-time monitoring of biologic changes in tumors may be possible by investigating the transitional cells such as circulating tumor cells (CTCs) and disseminated tumor cells in bone marrow (BM-DTCs). However, the small numbers of CTCs and the limited access to bone marrow aspirates in cancer patients pose major hurdles. The goal of this study was to determine whether breast cancer (BC) patient-derived xenograft (PDX) mice could provide a constant and renewable source of CTCs and BM-DTCs, thereby representing a unique system for the study of metastatic processes.

Methods

CTCs and BM-DTCs, isolated from BC PDX-bearing mice, were identified by immunostaining for human pan-cytokeratin and nuclear counterstaining of red blood cell-lysed blood and bone marrow fractions, respectively. The rate of lung metastases (LM) was previously reported in these lines. Associations between the presence of CTCs, BM-DTCs, and LM were assessed by the Fisher’s Exact and Cochran-Mantel-Haenszel tests. Two separate genetic signatures associated with the presence of CTC clusters and with lung metastatic potential were computed by using the expression arrays of primary tumors from different PDX lines and subsequently overlapped to identify common genes.

Results

In total, 18 BC PDX lines were evaluated. CTCs and BM-DTCs, present as either single cells or clusters, were detected in 83% (15 of 18) and 62.5% (10 to16) of the lines, respectively. A positive association was noted between the presence of CTCs and BM-DTCs within the same mice. LM was previously found in 9 of 18 (50%) lines, of which all nine had detectable CTCs. The presence of LM was strongly associated with the detection of CTC clusters but not with individual cells or detection of BM-DTCs. Overlapping of the two genetic signatures of the primary PDX tumors associated with the presence of CTC clusters and with lung metastatic potential identified four genes (HLA-DP1A, GJA1, PEG3, and XIST). This four-gene profile predicted distant metastases-free survival in publicly available datasets of early BC patients.

Conclusion

This study suggests that CTCs and BM-DTCs detected in BC PDX-bearing mice may represent a valuable and unique preclinical model for investigating the role of these rare cells in tumor metastases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0508-5) contains supplementary material, which is available to authorized users.

Outcome of metastatic breast cancer in selected women with or without deleterious BRCA mutations

The aim of this study was to compare the time-to progression and overall survival (OS) in patients with metastatic breast cancer (MBC) with and without deleterious BRCA1/2 mutations. 195 women with MBC who were referred for BRCA genetic testing between 1997 and 2011 were included in the study. Logistic regression models and Cox proportional hazards models were fit to determine the associations between clinical variables and outcomes. Of 195 women with MBC, 21 % (n = 41) were positive for BRCA1/2 mutations. The number of metastatic sites at the time of metastatic disease was not different between BRCA1 versus BRCA2 carriers versus non-carriers (P = 0.77). The site of first metastasis was visceral-only in 70 % of BRCA1 carriers compared to 9 % in BRCA2 carriers and 37 % in non-carriers (P = 0.001). Median follow-up was 2.8 years. BRCA non-carriers and BRCA2 carriers had a longer time-to progression and OS compared to BRCA1 carriers (median time-to progression = 1.3 vs. 0.9 vs. 0.7 years; P = 0.31, and median OS = 4.88 vs. 4.94 vs. 1.34 years; P = 0.0065). In a multivariate model, no association was identified between BRCA positivity and time-to-event outcomes (P > 0.28). In addition, patients with triple-negative MBC carried a poorer prognosis irrespective of their BRCA status (P = 0.058 and P = 0.15 for the interaction term of BRCA status and triple-negative for time-to progression and OS, respectively). Our data indicate that BRCA1 carriers diagnosed with MBC have worse outcomes compared to BRCA2 carriers and non-carriers. However, the differences in outcome did not reach statistical significance likely due to small sample sizes.

Therapeutic potential of PARP inhibitors for metastatic breast cancer

Increasing understanding of the cellular aberrations inherent to cancer cells has allowed the development of therapies to target biological pathways, an important step towards individualization of breast cancer therapy. The clinical development of poly(ADP-ribose) polymerase (PARP) inhibitors, with their novel and selective mechanism of action, are an example of this strategy. PARP plays a key role in DNA repair mechanisms, particularly the base excision repair pathway. Initially developed as inhibitors able to enhance the cytotoxicity of radiation and certain DNA-damaging agents, they have more recently been shown to have single-agent activity in certain tumors. Inhibition of PARP in a DNA repair-defective tumor can lead to gross genomic instability and cell death by exploiting the paradigm of synthetic lethality. Several studies have evaluated the role of PARP inhibitors for treatment of breast cancer, particularly in the context of BRCA-mutated and triple-negative breast cancers. In addition, inhibition of PARPs repair functions for chemotherapy-induced DNA lesions has been shown to potentiate the effect of some chemotherapy regimens. This article discusses the current understanding of PARP inhibition as a treatment for metastatic breast cancer, evidence from clinical trials and addresses its future implications.

Basal breast cancer: a complex and deadly molecular subtype

During the last decade, gene expression profiling of breast cancer has revealed the existence of five molecular subtypes and allowed the establishment of a new classification. The basal subtype, which represents 15-25% of cases, is characterized by an expression profile similar to that of myoepithelial normal mammary cells. Basal tumors are frequently assimilated to triple-negative (TN) breast cancers. They display epidemiological and clinico-pathological features distinct from other subtypes. Their pattern of relapse is characterized by frequent and early relapses and visceral locations. Despite a relative sensitivity to chemotherapy, the prognosis is poor. Recent characterization of their molecular features, such as the dysfunction of the BRCA1 pathway or the frequent expression of EGFR, provides opportunities for optimizing the systemic treatment. Several clinical trials dedicated to basal or TN tumors are testing cytotoxic agents and/or molecularly targeted therapies. This review summarizes the current state of knowledge of this aggressive and hard-to-treat subtype of breast cancer.

Breast cancer prognosis in BRCA1 and BRCA2 mutation carriers: an International Prospective Breast Cancer Family Registry population-based cohort study

PURPOSE

To compare breast cancer prognosis in BRCA1 and BRCA2 mutation carriers with that in patients with sporadic disease.

PATIENTS AND METHODS

An international population-based cohort study was conducted in Canada, the United States, and Australia of 3,220 women with incident breast cancer diagnosed between 1995 and 2000 and observed prospectively. Ninety-three had BRCA1 mutations; 71, BRCA2 mutations; one, both mutations; 1,550, sporadic breast cancer; and 1,505, familial breast cancer (without known BRCA1 or BRCA2 mutation). Distant recurrence and death were analyzed.

RESULTS

Mean age at diagnosis was 45.3 years; mean follow-up was 7.9 years. Risks of distant recurrence and death did not differ significantly between BRCA1 mutation carriers and those with sporadic disease in univariable and multivariable analyses. Risk of distant recurrence was higher for BRCA2 mutation carriers compared with those with sporadic disease in univariable analysis (hazard ratio [HR], 1.63; 95% CI, 1.02 to 2.60; P = .04). Risk of death was also higher in BRCA2 carriers in univariable analysis (HR, 1.81; 95% CI, 1.15 to 2.86; P = .01). After adjustment for age, tumor stage and grade, nodal status, hormone receptors, and year of diagnosis, no differences were observed for distant recurrence (HR, 1.00; 95% CI, 0.62 to 1.61; P = 1.00) or death (HR, 1.12; 95% CI, 0.70 to 1.79; P = .64).

CONCLUSION

Outcomes of BRCA1 mutation carriers were similar to those of patients with sporadic breast cancer. Worse outcomes in BRCA2 mutation carriers in univariable analysis seem to reflect the presence of more adverse tumor characteristics in these carriers. Similar outcomes were identified in BRCA2 carriers and those with sporadic disease in multivariable analyses.

Consensus on the utility of bone markers in the malignant bone disease setting

Biochemical markers of bone turnover provide insight into ongoing rates of skeletal metabolism and tumor-bone interactions in patients with malignant bone disease. This article reviews the available recent evidence assessing the potential of bone markers for detecting and monitoring malignant bone lesions in patients with advanced cancers, and for assessing overall skeletal health and response to antiresorptive therapies in patients at all stages of cancer progression. Most data thus far are for urinary N-terminal cross-linked telopeptide of type I collagen (NTX) in predicting risks of skeletal morbidity and death and monitoring response to zoledronic acid in patients with bone metastases. Ongoing studies are evaluating such correlations for other markers and therapies. Emerging evidence suggests that bone markers may help identify patients at high risk for bone metastasis or bone lesion progression, thereby allowing improved follow-up. Results from ongoing clinical trials evaluating such potential applications of bone markers are awaited.

Response to neoadjuvant systemic therapy for breast cancer in BRCA mutation carriers and noncarriers: a single-institution experience

PURPOSE

To compare the pathologic complete response (pCR) rate and relapse-free survival (RFS) and overall survival (OS) after neoadjuvant systemic chemotherapy (NST) in patients with breast cancer with and without deleterious BRCA1 and BRCA2 mutations.

PATIENTS AND METHODS

A total of 317 women who underwent BRCA genetic testing and were treated with NST for breast cancer between 1997 and 2009 were included in the study. The Kaplan-Meier product-limit method was used to estimate RFS and OS rates. Logistic regression models were fit to determine the associations between BRCA status, pCR, and survival.

RESULTS

Fifty-seven (18%) and 23 (7%) patients had BRCA1 and BRCA2 mutations, respectively. Twenty-six (46%) of 57 BRCA1 carriers achieved a pCR, compared with three (13%) of 23 BRCA2 carriers and 53 (22%) of 237 BRCA noncarriers (P < .001). In the multivariate logistic model, BRCA1 status (odds ratio [OR] = 3.16; 95% CI, 1.55 to 6.42; P = .002), estrogen receptor (ER) negativity (OR = 1.96; 95% CI:1.05 to 3.65; P = .03) and concurrent trastuzumab use (OR = 4.18; 95% CI, 2.04 to 8.57; P < .001) remained as independent significant predictors for a pCR. At a median follow-up of 3.2 years, 69 patients (22%) experienced a disease recurrence or death. No significant differences were noted in survival outcomes with respect to BRCA status and type of NST received. However, among BRCA1 carriers, patients who achieved a pCR had better 5-year RFS (P = .001) and OS (P = .01) rates than patients who did not.

CONCLUSION

BRCA1 status and ER negativity are independently associated with higher pCR rates in patients with breast cancer. Overall prognosis of breast cancer in BRCA carriers is similar to sporadic breast cancers.

Outcome of triple-negative breast cancer in patients with or without deleterious BRCA mutations

More than 75% of breast cancers that develop in BRCA1 mutation carriers are triple-negative breast cancers (TNBC). The aim of this study was to compare the recurrence-free survival (RFS) and overall survival (OS) in high-risk patients with TNBC with and without deleterious BRCA1/2 mutations. A total of 227 women with TNBC who were referred for genetic counseling and underwent BRCA genetic testing between 1997 and 2010 were included in the study. The relationships between clinical variables and outcomes were evaluated using univariate and multivariate Cox proportional hazard regression models. Of 227 high-risk women with TNBC, 50% (n = 114) tested positive for BRCA1/2 mutations. Age, race, and tumor characteristics did not differ between BRCA non-carriers and carriers. At a median follow-up of 3.4 years, the 5-year RFS rates were 74 and 81% (P = 0.21), and 5-year OS rates were 85 and 93% in BRCA non-carriers and BRCA carriers, respectively (P = 0.11). In a multivariate model, after adjusting for age and disease stage, BRCA carriers tended to have a decreased risk of recurrence (HR = 0.67; 95% CI: 0.38-1.19; P = 0.17) or death (HR = 0.51; 95% CI:0.23-1.17; P = 0.11) compared to non-carriers. Our data indicate a 50% prevalence of deleterious BRCA1/2 mutations in high-risk women diagnosed with TNBC. Overall prognosis of TNBC in BRCA carriers and non-carriers is not significantly different within the first 5 years following an initial diagnosis. Further studies need to evaluate whether different therapies will change the outcome in these subgroups of TNBC.

Breast carcinomas with isolated bone metastases have different hormone receptor expression profiles than those with metastases to other sites or multiple organs

Breast carcinoma (BC) is one of the most common osteotropic tumors. The subset of BC patients with isolated bone metastasis (IBM) forms a clinically distinct group and often has a favorable clinical outcome as compared to others with metastatic BC. We analyzed all BC patients with distal organ metastasis in our institution between 1997 and 2003 (N = 198) to identify the clinicopathologic features of BC with IBM and compare them to those with metastasis to other sites. We found that 63% of BC patients with advanced disease had bone metastases, and 44% of those were IBM. The proportion of cases with IBM that expressed estrogen receptor and/or progesterone receptor (47/52; 90%) was significantly higher than those with non-bone metastases (P < .0001) and than those with multiple metastases involving bone (P < .0001). The distribution of BC molecular subtypes in cases of IBM was again significantly different from that of the remainder. By univariate and multivariate analysis of the clinicopathologic factors examined, only estrogen receptor and progesterone receptor status of the primary tumor was predictive for IBM. The median survival after diagnosis of metastatic disease was significantly longer in cases with IBM than that of any other group. Our results indicate that the diversity in receptor expression patterns not only reflects the biological diversity of mammary tumors but may also predict their metastatic potential and thus could potentially be used in surveying women patients with nonmetastatic disease.

Incidence and outcome of BRCA mutations in unselected patients with triple receptor-negative breast cancer

PURPOSE

To investigate the incidence of germline and somatic BRCA1/2 mutations in unselected patients with triple-negative breast cancer (TNBC) and determine the prognostic significance of carrying a mutation.

METHODS

DNA was obtained from 77 TNBC and normal tissues. BRCA1/2 exons/flanking regions were sequenced from tumor and patients classified as mutant or wild type (WT). Sequencing was repeated from normal tissue to identify germline and somatic mutations. Patient characteristics were compared with chi-square. Survival was estimated by Kaplan-Meier method and compared with log-rank. Cox proportional hazards models were fit to determine the independent association of mutation status with outcome.

RESULTS

Median age was 51 years (27-83 years). Fifteen patients (19.5%) had BRCA mutations: 12 (15.6%) in BRCA1 (one somatic), and 3 (3.9%) in BRCA2. Patients with BRCA mutations tended to be younger than WT, (P = 0.005). Grade, histology, and stage were not associated with mutation status. At a median follow-up of 43 months (7-214 months), there were 33 (42.9%) recurrences and 35 (45.5%) deaths. Five-year recurrence-free survival estimates were 51.7% for WT versus 86.2% for patients with mutations, (P = 0.031); and 5-year overall survival estimates were 52.8% for WT versus 73.3% for patients with mutations (P = 0.225). After adjustment, patients with BRCA mutations had a significantly better RFS (HR: 0.19, 95% CI: 0.045-0.79, P = 0.016) compared with WT.

CONCLUSIONS

In this unselected cohort of TNBC, we found a 19.5% incidence of BRCA mutations. Genetic testing should be discussed with patients with TNBC. Patients with TNBC with BRCA mutations had a significantly lower risk of relapse.

Pathology of hereditary breast cancer

Background

Hereditary breast cancer runs in families where several members in different generations are affected. Most of these breast cancers are caused by mutations in the high penetrance genes BRCA1 and BRCA2 accounting for about 5% of all breast cancers. Other genes that include CHEK2, PTEN, TP53, ATM, STK11/LKB1, CDH1, NBS1, RAD50, BRIP1 and PALB2 have been described to be high or moderate penetrance breast cancer susceptibility genes, all contributing to the hereditary breast cancer spectrum. However, in still a part of familial hereditary breast cancers no relationship to any of these breast cancer susceptibility genes can be found. Research on new susceptibility genes is therefore ongoing.

Design

In this review we will describe the function of the today known high or moderate penetrance breast cancer susceptibility genes and the consequences of their mutated status. Furthermore, we will focus on the histology, the immunophenotype and genotype of breast cancers caused by mutations in BRCA1 and BRCA2 genes and the other high or moderate penetrance breast cancer susceptibility genes. Finally, an overview of the clinical implications of hereditary breast cancer patients will be provided.

Conclusion

This information leads to a better understanding of the morphological, immunohistochemical and molecular characteristics of different types of hereditary breast cancers. Further, these characteristics offer clues for diagnosis and new therapeutic approaches.

Germline genetic variation, cancer outcome, and pharmacogenetics

Studies of the role of germline or inherited genetic variation on cancer outcome can fall into three distinct categories. First, the impact of highly penetrant but lowly prevalent mutations of germline DNA on cancer prognosis has been studied extensively for BRCA1 and BRCA2 mutations as well as mutations related to hereditary nonpolyposis colorectal cancer syndrome. These mainly modest-sized analyses have produced conflicting results. Although some associations have been observed, they may not be independent of other known clinical or molecular prognostic factors. Second, the impact of germline polymorphisms on cancer prognosis is a burgeoning field of research. However, a deeper understanding of potentially confounding somatic changes and larger multi-institutional, multistage studies may be needed before consistent results are seen. Third, research examining the impact of germline genetic variation on differential treatment response or toxicity (pharmacogenetics) has produced some proof-of-principle results. Putative germline pharmacogenetic predictors of outcome include DPYD polymorphisms and fluorouracil toxicity, UGT1A1 variation and irinotecan toxicity, and CYP2D6 polymorphisms and tamoxifen efficacy, with emerging data on predictors of molecularly targeted or biologic drugs. Here we review data pertaining to these germline outcome and germline toxicity relationships.

Clinical relevance of the triple-negative breast cancer concept: genetic basis and clinical utility of the concept

The beginning of microarray technology in the 1990s and the sequencing of the human genome in 2000 paved the way for the seminal paper of the Stanford group on the molecular portraits of human breast tumours in the same year. They described four distinct breast cancer subtypes, which they called 'luminal', 'basal', 'HER2-positive', and 'normal breast-like', based on unique gene expression patterns. This paper caused a paradigm shift. Breast cancer was no longer hormone receptor-positive or -negative, but rather luminal, basal or HER2-positive. Since then, numerous papers have appeared, trying to further characterise these subtypes on the DNA, RNA and protein level. Other groups have focussed on the epidemiology, prognosis and outcome after therapy of breast cancer patients according to these molecular subtypes. A promising prognostic marker within the subgroup of basal-like breast cancer is an up-regulated immune response, which is associated with favourable outcome. In addition, the majority of basal-like breast cancers harbour traits of a DNA damage repair defect. This feature can be exploited by the use of DNA damaging agents, and first exciting clinical results of the combination of carboplatin, gemcitabine and a poly (ADP-ribose) polymerase 1 (PARP-1) inhibitor have recently been reported. In this review, the molecular characterisation of triple-negative breast cancer, a proxy for basal-like breast cancer, is described and findings have been put into clinical context.

Sensitivity to First-Line Chemotherapy for Metastatic Breast Cancer in BRCA1 and BRCA2 Mutation Carriers

Purpose

Preclinical as well as a few small retrospective, neoadjuvant studies suggest that breast cancer (cells) without functional BRCA1 or BRCA2 protein have an increased sensitivity to some chemotherapeutic agents causing double-strand DNA breaks. In this study we assessed the sensitivity to standard first-line chemotherapy of metastatic BRCA1/2-associated breast cancer, compared with sporadic breast cancer patients.

Patients and Methods

From the Family Cancer Clinic database, we selected 93 BRCA1- and 28 BRCA2-associated breast cancer patients treated with chemotherapy for metastatic disease before January 1, 2007. Objective response (OR), progression-free survival (PFS), and overall survival (OS) after start of first-line chemotherapy were compared with those of sporadic patients, matched for year of birth, age at diagnosis of primary breast cancer, and year of detection of metastatic disease.

Results

The chemotherapy regimens most frequently used were anthracycline-based (n = 147) and cyclophosphamide, methotrexate, and fluorouracil (CMF)/CMF like (n = 68). As compared to sporadic patients, BRCA2-associated patients had a significantly higher OR (89% v 50%; P = .001), a longer PFS (hazard ratio multivariate [HRmult] 0.64; P = .04) and a prolonged OS (HRmult, 0.53; P = .005) after start of first-line chemotherapy for metastatic breast cancer. For BRCA1-associated patients, a nonsignificant trend for an increased OR (66% v 50%; P = .07), and a longer PFS (HRmult, 0.79; P = .14) after first-line chemotherapy for metastatic breast cancer was observed, but not for OS.

Conclusion

BRCA2-associated breast cancer is more sensitive to standard first-line chemotherapy for metastatic breast cancer in comparison with sporadic breast cancer, especially to anthracyclines. For BRCA1-associated breast cancer no statistically significant higher sensitivity was observed.

Triple-negative breast cancer: risk factors to potential targets

Triple-negative breast cancer has recently been recognized as an important subgroup of breast cancer with a distinct outcome and therapeutic approach when compared with other subgroups of breast cancer. Triple-negative breast cancer comprises primarily, but not exclusively, a molecularly distinct subtype of breast cancer, the basal-like subtype. We do not yet have an assay to identify basal-like breast cancer in clinical samples, so triple-negative breast cancer has become a commonly used proxy for this subtype. The molecular biology and pathophysiology of triple-negative breast cancer are not completely understood, but understanding is improving rapidly with the advent of sophisticated molecular biology platforms. Moreover, the established risk factors of breast cancer as a whole may not apply to this unique subgroup of patients. Finally, because triple-negative breast cancer is defined by the absence of a target, there are currently limitations to using a tailored therapeutic approach, leaving conventional cytotoxic therapies as the mainstay. Active preclinical and clinical research programs focus on defining the clinical behavior, delineating the risk factors, and more completely understanding the molecular biology of triple-negative breast cancer to improve prevention, optimize conventional agents, and unveil novel therapeutic targets. This CCR focus article will review the current state of the art on triple-negative breast cancer.