Interphase cytogenetics of chromosomes 11 and 17 in fine needle aspirates of breast cancer

Frequency of chromosome 17 polysomy in relation to CEP17 copy number in a large breast cancer cohort

Eligibility to anti-HER2 therapy for breast tumors strictly depends on demonstrating HER2 overexpression (by immunohistochemistry) or HER2 gene amplification by in situ hybridization (ISH), usually defined by the ratio of HER2 gene to chromosome 17 centromere (CEP17) copies. However, the CEP17 copy number increase (CNI) has been proven responsible for misleading HER2 FISH results and recent small cohort studies suggest that chromosome 17 polysomy is actually very rare. Here we investigated by FISH the frequency of true chromosome 17 polysomy in a consecutive cohort of 5,477 invasive breast cancer patients. We evaluated and selected the LSI 17p11.2 probe for chromosome 17 enumeration on a training cohort of 67 breast cancer samples (CEP17 ≥ 2.5). LSI 17p11.2 was used in the 297/5,477 patients from the validation cohort displaying CEP17 CNI (CEP17 ≥ 3.0). Using HER2/17p11.2 scoring criteria, 37.3%/1.5% patients initially classified as equivocal/non-amplified were reclassified as amplified. For a more accurate assessment of chromosome 17 and ploidy in the samples, we tested six markers located on chromosome 17 and centromeric regions of chromosome 8 (CEP8) and 11 (CEP11) in 67 patients with CEP17 and LSI 17p11.2 CNI. True polysomy (hyperdiploidy) according to these markers was found in 0.48% of cases (24/5,020). CEP8 and CEP11 CNI (≥3.0) was more frequent in the hyperdiploid than CEP17 non-polysomic group (55.6% vs. 6.1% and 25% vs. 2.3%, respectively). Our results suggest that chromosome 17 polysomy is a rare event found in <1% breast cancer cases and that polysomy of other chromosomes frequently occurs with chromosome 17 polysomy.

Fluorescence in situ hybridization as adjunct to cytology improves the diagnosis and directs estimation of prognosis of malignant pleural effusions

Background

The identification of malignant cells in effusions by conventional cytology is hampered by its limited sensitivity and specificity. The aim of this study was to investigate the value of fluorescence in situ hybridization (FISH) as adjuncts to conventional cytologic examination in patients with malignant pleural effusions.

Methods

We conducted a retrospective cohort study of 93 inpatients with pleural effusions (72 malignant pleural effusions metastatic from 11 different organs and 21 benign) over 23 months. All the patients came from Chinese northeast areas. Aspirated pleural fluid underwent cytologic examination and fluorescence in situ hybridization (FISH) for aneuploidy. We used FISH in single-colour or if appropriate in dual-colour evaluation to detect chromosomal aberrations (chromosomes 7, 11, and 17) in effusion cells as markers of malignancy, to raise the diagnostic yield and identified the efficiency by diagnostic biopsy. Predominant cytogenetic anomalies and patterns of intratumor cytogenetic heterogeneity were brought in relation to overall survival rate.

Results

Cytology alone confirmed malignant pleural effusions in 45 of 72 patients (sensitivity 63%), whereas FISH alone positively identified 48 of 72 patients (sensitivity 67%). Both tests had high specificity in predicting benign effusions. If cytology and FISH were considered together, they exhibited 88% sensitivity and 94.5% specificity in discriminating benign and malignant effusions. Combined, the two assays were more sensitive than either test alone. Although the positive predictive value of each test was 94.5%, the negative predictive value of cytology and FISH combined was 78%, better than 47% and 44% for FISH and cytology alone, respectively. There was a significantly prolonged survival rate for patients with aneuploidy for chromosome 17.

Conclusions

FISH in combination with conventional cytology is a highly sensitive and specific diagnostic tool for detecting malignant cells in pleural effusions . The high sensitivity and specificity may be associated with geographic area and race. Simple numeric FISH anomalies may be prognostic.

Prognostic value of TOP2A gene amplification and chromosome 17 polysomy in early breast cancer

The aim of this study was to analyze the occurrence of TOP2A gene amplification and chromosome 17 polysomy in patients with early breast cancer and to correlate the status of these alterations with the prognostic significance expressed as patients' clinical features and survival. Such concurrent analyses of TOP2A gene status and chromosome 17 polysomy have not been performed before. Study group included 149 consecutive stage I-III patients administered standard multimodality treatment. TOP2A abnormalities were examined by standard fluorescence in situ hybridization (FISH) and developed by our group quantitative real-time PCR (qPCR). TOP2A amplification and deletion assessed by FISH were found in 23% and 7% of the tumours, respectively, and by qPCR in 31% and 11% of the tumours, respectively. Chromosome 17 polysomy was detected in 40% of the cases. TOP2A amplification (by qPCR) correlated with shorter disease-free survival (p = 0.03) and overall survival (p = 0.047), and the prognostic value of TOP2A was confirmed in the multivariate analysis (HR = 3.22, 95% CI 1.09-9.56, p = 0.03). TOP2A gene amplification, but not chromosome 17 polysomy, carries negative prognostic information in early breast cancer. Given the aforementioned results, qPCR might serve as a prognostic tool in determining the patient's prognosis.

Breast cancer and aneusomy 17: implications for carcinogenesis and therapeutic response

Abnormalities of chromosome 17, recognised over two decades ago to be important in tumorigenesis, often occur in breast cancer. Changes of specific loci on chromosome 17 including ERBB2 amplification, P53 loss, BRCA1 loss, and TOP2A amplification or deletion are known to have important roles in breast-cancer pathophysiology. Numerical aberrations of chromosome 17 are linked to breast-cancer initiation and progression, and possibly to treatment response. However, the clinical importance of chromosome 17 anomalies, in particular the effect on ERBB2 protein expression, is unknown. Reports are conflicting regarding the association of copy gain of chromosome 17 (polysomy 17) with strong ERBB2 protein expression in the absence of true ERBB2 gene amplification. Copy-number anomalies in chromosome 17 seem to be common in tumours that show discrepant ERBB2 expression and in tumours with discordant ERBB2-protein and ERBB2 gene copy number measurements. The mechanisms of ERBB2 dosage changes-gene amplification versus chromosome gain and loss-probably differ in primary and metastatic disease; however, a correction for chromosome 17 copy-number is necessary to completely distinguish between these mechanisms. A better understanding of how polysomy 17 affects gene-copy number and protein expression will help to select patients who will respond to therapies targeting ERBB2 and other protein products of chromosome 17 loci.

Numerical aberrations of chromosomes 1 and 7 by fluorescent in situ hybridization and DNA ploidy analysis in breast cancer

The goals of this study were to detect the numerical alterations of chromosomes 1 and 7 in breast cancer and to correlate the findings with DNA ploidy status as well as with parameters of prognostic significance. Fluorescence in situ hybridization (FISH) with centromeric probes for chromosomes 1 and 7 and cellular DNA content measurement by image analysis-based cytophotometry were applied on interface nuclei from fresh tissue imprints of 59 breast ductal carcinomas. Immunohistochemical stainings for estrogen receptor (ER), progesterone receptor (PR), HER-2, p53, and Ki67 were performed on paraffin tumor sections. The correlation between DNA ploidy and chromosomal aberrations revealed a significant association between aneuploidy and aneusomy for both chromosomes 1 (p=0.002) and 7 (p=0.00001), however, a number of diploid tumors were found to be aneusomic, especially for chromosome 1. Chromosome 7 polysomy was significantly associated with a higher incidence of axillary lymph node metastasis (p=0.05), poorly differentiated (grade III) tumors (p=0.03), negative ER and PR status (p=0.02 and 0.001, respectively), as well as p53 protein expression (p=0.05) and a higher Ki67 labeling index (p=0.004). Chromosome 1 aneusomy was only related with HER-2 protein overexpression (p=0.05). No association between chromosome alterations and tumor size was detected. In conclusion, the results of our study indicate that the detection of numerical aberrations of chromosomes 1 and 7 by FISH seems to be more sensitive than DNA ploidy status for the evaluation of abnormal cellular DNA and chromosome 7 aneusomy characterizes tumors with aggressive features and therefore might be a useful predictor of unfavorable biological behavior in breast cancer.

The influence of polysomy 17 on HER2 gene and protein expression in adenocarcinoma of the breast: a fluorescent in situ hybridization, immunohistochemical, and isotopic mRNA in situ hybridization study

Breast carcinomas with amplification of HER2 on chromosome 17 are associated with HER2 protein overexpression, adversely affecting prognosis and predicting response to Herceptin therapy. Chromosome 17 polysomy is encountered in assessing HER2 gene status, and its impact on HER2 gene and protein expression remains unclear. This impact was investigated in breast carcinomas identified by fluorescence in situ hybridization (FISH) to have a gain of chromosome 17 (CEP17+; n = 56), using a dual probe assay, which detects HER2 gene copy number and enumerates chromosome 17 (HER2/CEP17; Vysis). Cases were immunostained for HER2 protein (CB-11, Ventana), and scored blinded to FISH. A subgroup was evaluated by isotopic in situ hybridization for HER2 mRNA expression. Controls included ten HER2 amplified and ten nonamplified tumors, eusomic for chromosome 17. Immunohistochemistry (IHC) for HER2 protein was negative (0 or 1+) in 69% (39 of 56), 2+ in 27% (15 of 56), and 3+ in 3% (2 of 56) of CEP17+ cases. The mean CEP17 copy number among the three groups was similar (3.1, 3.0, and 3.1 for IHC 0/1+, 2+, and 3+, respectively). Isotopic in situ hybridization for HER2 mRNA performed on 26 CEP17+ cases (16 IHC 0-1+, 10 IHC 2+ or 3+) showed no increased HER2 mRNA expression (normalized to beta-actin mRNA). The mRNA expression and the IHC staining of the HER2-amplified and nonamplified controls was concordant with their FISH status. These results suggest that chromosome 17 polysomy in the absence of HER2 amplification does not have a significant biologic influence on HER2 gene expression in breast carcinoma.

Feasibility and utility of using chromosomal aneusomy to further define the cytologic categories in nipple aspirate fluid specimens

BACKGROUND

There is renewed interest in using the cytologic changes in the epithelial cells obtained from specimens such as nipple aspiration fluid (NAF) and ductal lavage for risk stratification of women at increased risk for developing breast carcinoma.

METHODS

Molecular tests such as fluorescence in situ hybridization (FISH) have the potential to be used as adjuncts to conventional cytology for more accurately categorizing cells in these types of specimens. The current study investigated the feasibility and utility of FISH analysis of aneusomy in chromosomes 1, 8, 11 and 17 as an adjunct to conventional cytology in the classification of NAF specimens.

RESULTS

The authors found chromosomal aneusomy for at least one chromosome in all three malignant and both markedly atypical cases. Of the five cases classified as being mildy atypical on cytology, four were disomic, and only one showed aneusomy in chromosomes 8 and 11.

CONCLUSIONS

The current study established the possibilities, limitations, and feasibility of using FISH in conjunction with routine cytology for a more accurate classification of ductal epithelial cells in NAF specimens. FISH-based detection of chromosomal aneusomy helped to define mild atypia, thereby aiding in the selection of the truly atypical cases for appropriate therapeutic intervention. In addition, FISH-based detection of chromosomal aneusomy can also be a valuable adjunct to conventional cytology in selected cases for confirming a benign, suspicious, or malignant diagnosis.

Chromosome 17 aneusomy is associated with poor prognostic factors in invasive breast carcinoma

Aberrations of chromosome 17 are common in breast cancer. Fluorescence in situ hybridization (FISH) enables gene or chromosome copy number to be assessed in situ in archival tissues and related to morphology and clinical outcome. In this study direct labeled DNA probes for the chromosome 17 alpha satellite and the HER2/neu gene were applied simultaneously to 5 micron sections of 214 formalin-fixed paraffin-embedded invasive primary breast carcinomas. A high proportion (54%) of invasive breast carcinomas displayed aneusomy of chromosome 17. Polysomy 17 correlated with multiple copies of HER2/neu (p = < 0.001), but not with HER2/neu amplification. Eighty-six patients without HER2/neu amplification had aneusomy 17. Fifty-eight of the 86 patients that had aneusomy 17 had high HER2/neu copy number. Twelve patients with normal copy number for chromosome 17 had amplification of HER2/neu and 30 patients had amplification of HER2/neu with aneusomy 17. Aneusomy 17 was associated with grade 3 carcinoma (p = 0.008), ER negativity (p = 0.0032) and a Nottingham prognostic index of greater than 5.4 (p = 0.039) but was not associated with survival by univariate analysis. In conclusion, the determination of chromosome 17 copy number should be incorporated in assessment of HER2/neu status, as this will give an accurate measure of amplification of HER2/neu and may also be helpful in determining suitability for breast carcinoma trials.

Evaluation of numeric alterations of chromosomes 1 and 17 by in situ hybridization in invasive breast carcinoma with clinicopathologic parameters

Breast cancer is a genetically complex disease and is frequently associated with nonrandom chromosomal alterations. The occurrence of aberrations involving chromosomes 1 and 17 in malignant tissues of breast cancer patients has not been studied systematically. The numeric aberrations of chromosomes 1 and 17 were detected by nonisotopic in situ hybridization on paraffin-embedded tissue sections from 44 invasive breast carcinomas (42 cases available for chromosome 17) and were correlated with clinicopathologic parameters, patients' survival, p53, and c-erbB-2 proteins. Chromosome 17 and 1 aneuploidy were observed in the majority of breast carcinomas with equal percentages of polysomy and monosomy for chromosome 17 and predominance of polysomy for chromosome 1. Monosomy of chromosome 17 was significantly associated with positive lymph nodes and negative estrogen receptor (ER) immunohistochemical expression. Patients with chromosome 17 monosomy were at greater risk of death. Ductal carcinoma displayed a greater percentage of chromosome 1 polysomy than lobular ones. A statistically significant association was demonstrated between chromosome 1 polysomy and higher nuclear grade. Patients with chromosome 1 aneuploidy were at greater risk of death, and especially those with ER negativity. Aneuploid patients with c-erbB-2(-)/PR(-) phenotype demonstrated lower survival rates. These data suggest a possible susceptibility of chromosome 17 to losses and gains and chromosome 1 to gains. Chromosome 17 monosomy and chromosome 1 aneuploidy may be useful prognostic markers in breast cancer patients.

Clinicopathologic analysis of breast carcinoma with chromosomal aneusomy detected by fluorescence in situ hybridization

BACKGROUND

The clinicopathologic characteristics of breast carcinoma with chromosomal aneusomy detected by fluorescence in situ hybridization (FISH) have yet to be clarified.

METHODS

Fine-needle aspiration biopsy (FNAB) samples were obtained from 113 breast tumors and were subjected to FISH analysis using centromeric probes for chromosomes 1, 11, and 17 to study a numerical aberration of these chromosomes and its correlation with various clinicopathologic features of breast tumors.

RESULTS

Polysomy was observed in 77.0%, 50.5%, and 37.2% of breast carcinoma samples for chromosomes 1, 11, and 17, respectively, and monosomy was observed in 1.8%, 8.8%, and 22.1% for chromosomes 1, 11, and 17, respectively. High histologic grade showed a significant correlation (P < 0.05) with polysomy of chromosome 11. Lymph node metastasis showed a significant correlation (P < 0.05) with polysomy of all three chromosomes, and positivity of lymph node metastasis increased as the number of polysomic chromosomes increased. In addition, estrogen receptor negativity was correlated significantly (P < 0.05) with monosomy of chromosome 17, and progesterone receptor negativity was correlated significantly (P < 0.05) with polysomy of chromosomes 11 and 17.

CONCLUSIONS

Aneusomy of chromosome 1, 11, or 17 detected by FISH is correlated significantly with various clinicopathologic features of breast carcinoma. Because FISH analysis of chromosomal aneusomy can be done using FNAB samples, this technique seems to have the potential to be used for a better, preoperative definition of the biologic characteristics of breast tumors.

Malignant cell detection by fluorescence in situ hybridization (FISH) in effusions from patients with carcinoma

Cytological diagnosis of malignant cells in effusions is hampered by difficulties in the differentiation from reactive mesothelial cells. Because interphase cytogenetics by fluorescence in situ hybridization (FISH) might complement cytological evaluation, we determined the power of tumor cell detection using FISH and cytology in 201 effusions from patients with advanced cancer. Furthermore, 9 primary breast tumors were FISH-karyotyped, and chromosomal aberrations were compared with those of corresponding metastatic effusion cells. By using centromeric probes representing chromosomes 7, 8, 11, 12, 17, and 18, a rate of malignancy-associated aneusomy combined for the 6 chromosomes was detected in an overall of 44.8% of effusion specimens (range, 31.8% to 39.3% for the individual chromosome), comparable to cytology (43.3%). The combination of just 2 FISH probes (namely, representing chromosome pairs 8/11 and 8/17) was almost equally efficient in the identification of aneusomy. Approximately one fourth of the cytologically negative effusions were FISH positive and vice versa. From the initially FISH-negative effusions, 18.9% could be subsequently classified positive with dual-color FISH by visualization of intranuclear chromosomal complexity in rare aneuploid cells. Thus, "overall FISH analysis," including dual-color evaluation, identified tumor cells in significantly more effusions (55.2%, P = .001) than conventional cytology, implying greater sensitivity. Finally, our finding that numerical aberration patterns in primary breast tumors and corresponding metastatic effusions are comparable indicates that FISH examination of primary tumors will indicate the centromeric probe(s) best suited for an efficient search for metastasis in the individual case.