Familial breast/ovarian cancer and BRCA1/2 genetic screening: the role of immunohistochemistry as an additional method in the selection of patients

Surface Plasmon Resonance (SPR) Sensor for Cancer Biomarker Detection

A biomarker is a physiological observable marker that acts as a stand-in and, in the best-case scenario, forecasts a clinically significant outcome. Diagnostic biomarkers are more convenient and cost-effective than directly measuring the ultimate clinical outcome. Cancer is among the most prominent global health problems and a major cause of morbidity and death globally. Therefore, cancer biomarker assays that are trustworthy, consistent, precise, and verified are desperately needed. Biomarker-based tumor detection holds a lot of promise for improving disease knowledge at the molecular scale and early detection and surveillance. In contrast to conventional approaches, surface plasmon resonance (SPR) allows for the quick and less invasive screening of a variety of circulating indicators, such as circulating tumor DNA (ctDNA), microRNA (miRNA), circulating tumor cells (CTCs), lipids, and proteins. With several advantages, the SPR technique is a particularly beneficial choice for the point-of-care identification of biomarkers. As a result, it enables the timely detection of tumor markers, which could be used to track cancer development and suppress the relapse of malignant tumors. This review emphasizes advancements in SPR biosensing technologies for cancer detection.

Habitat Analysis of Breast Cancer-Enhanced MRI Reflects BRCA1 Mutation Determined by Immunohistochemistry

Objective

To use habitat analysis (also termed habitat imaging) for classifying untreated breast cancer-enhanced magnetic resonance imaging (MRI) in women. Moreover, we intended to obtain clustering parameters to predict the BReast CAncer gene 1 (BRCA1) gene mutation and to determine the use of MRI as a noninvasive examination tool.

Methods

We obtained enhanced MRI data of patients with breast cancer before treatment and selected some sequences as the source of habitat imaging. We used the k-means clustering to classify these images. According to the formed subregions, we calculated several parameters to evaluate the clustering. We used immunohistochemistry to detect BRCA1 mutations. Moreover, we separately determined the ability of these parameters through independent modeling or multiple parameter joint modeling to predict these mutations.

Results

Of all extracted values, separation (SP) demonstrated the best prediction performance for a single parameter (area under the receiver operating characteristic curve (AUC), 0.647; 95% confidence interval (CI), 0.557–0.731). Simultaneously, models based on the Calinski-Harabasz Index and sum of square error performed better in the training (AUC, 0.903; 95% CI, 0.831–0.96) and verification (AUC, 0.845; 95% CI, 0.723–0.942) sets for multiparameter joint modeling.

Conclusion

Based on the enhanced MRI of breast tumors and the subregions generated according to the habitat imaging theory, the parameters extracted to describe the clustering effect could reflect the BRCA1 status. Differences between clusters, including the general differences of cluster centers and clusters and the similarity of samples within clusters, were the embodiment of this mutation. We propose an algorithm to predict the BRCA1 mutation of a patient according to the enhanced MRI of the breast tumor.

Prognostic Relevance of BRCA1 Expression in Survival of Patients With Cervical Cancer

Objective

BRCA1 expression can be lost by a variety of mechanisms including germline or somatic mutation and promotor hypermethylation. Given the potential importance of BRCA1 loss as a predictive and prognostic biomarker in several cancers, the objective of this study was to investigate BRCA1 expression using immunohistochemistry (IHC) in cervical cancer and its possible prognostic relevance.

Methods

Seventy patients with cervical cancer were enrolled in this study. Samples from each tumor were stained for BRCA1 and reviewed independently by gynecologic pathologists blinded to the BRCA status. Kaplan-Meier methods were used to estimate overall survival according to BRCA1 expression. Differentially expressed genes (DEGs) by BRCA1 expression were selected using GSE44001 dataset, which included 300 samples treated with radical hysterectomy. In addition, cox regression analysis with backward elimination was performed to select independent prognostic markers. Gene set enrichment analysis (GSEA) was done using these DEGs.

Results

BRCA1 IHC was positive in 62.9% (44/70) of cases. Patients with BRCA1 expression showed better overall survival (100% vs. 76.2%, HR 0.20, 95% CI 0.04 - 0.99, p = 0.028) than those without BRCA1 expression. Analysis of gene expression profiles according to BRCA1 expression identified 321 differentially expressed mRNAs. Gene set enrichment analysis results showed two dysregulated pathways (VEGF_A_UP.V1_DN and E2F1_UP.V1_UP). Of these DEGs, alterations of 20 gene signatures were found to be independently associated with survival outcomes of patients.

Conclusions

BRCA1 expression in cervical cancer tissue is associated with survival. In addition, the identification of specific gene alterations associated with BRCA1 expression could help to provide individualized prediction in these patients.

BRCA immunohistochemistry for screening of BRCA mutation in epithelial ovarian cancer patients

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BRCA immunohistochemistry is simple, less expensive and widely available.

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Negative BRCA1 and/or BRCA2 expression was found in 34 patients (32.4%).

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BRCA immunohistochemistry has high negative predictive value of 96%.

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It may be useful to exclude patients without BRCA dysfunction.

To evaluate BRCA1/2 immunohistochemistry (IHC) as a screening test for germline BRCA1/2 in epithelial ovarian cancer (EOC), tumor tissue from 105 EOC patients who had germline BRCA mutations, including 9 BRCA1 mutations, 6 BRCA2 mutations and 90 no BRCA mutations, were studied. Paraffin-embedded tissue blocks were stained for BRCA1 and BRCA2. Tumors were indicated as a loss of BRCA expression when neoplastic nuclear stained less than 10%. Loss of BRCA1 and/or BRCA2 expression was found in 36 patients (34.3%). BRCA1 IHC loss was found in 21 patients (20%) while 24 patients (22.9%) had BRCA2 IHC loss. There were no significant differences in patient characteristics between both groups. Loss of BRCA1 expression had 66.7% sensitivity, 84.3% specificity, 28.6% positive predictive value (PPV), and 96.4% negative predictive value (NPV) for detection of germline BRCA1 mutation. Meanwhile, loss of BRCA2 expression had 50% sensitivity, 78.8% specificity, 12.5% PPV, and 96.3% NPV for detection of germline BRCA2 mutation. There was no significant difference in survival outcomes between both groups.

Based on high NPV, BRCA IHC may be useful to exclude patients without BRCA dysfunction if IHC showed intact expression. Only patients with BRCA IHC loss should be offered further genetic testing.

Immunohistochemistry for the detection of BRCA1 and BRCA2 proteins in patients with ovarian cancer: a systematic review

BACKGROUND

Loss of function in either breast cancer type 1 susceptibility protein (BRCA1) or breast cancer type 2 susceptibility protein (BRCA2) is a major risk factor for epithelial ovarian cancer (EOC) development. BRCA1 or BRCA2 deficiencies are associated with short-term prognosis and might have importance for the treatment of women with the disease. However, the screening of all possible mechanisms of dysfunction is expensive, time-consuming and difficult to apply in clinical practice. On the other hand, immunohistochemistry (IHC) is a simple and reliable method to access the expression of several proteins in tumour tissues.

MATERIALS AND METHODS

This systematic review aims to evaluate the current usage of IHC to detect BRCA1 and BRCA2 deficiencies in EOC. We searched and evaluated all primary literature on the use of IHC for evaluating BRCA1 and BRCA2 proteins expression in EOC. The main concepts for the search were: ovarian neoplasms, IHC, BRCA1 and BRCA2.

RESULTS

Forty-four studies from 925 unique titles were included. A total of 4206 tumour samples were evaluated for BRCA1 and 1041 for BRCA2 expression. Twelve BRCA1 primary antibodies were used in 41 studies, and the most common was the MS110 clone (75.6%). Seven BRCA2 primary antibodies were used in ten studies. Using the cut-off of 10%, 47.0% of EOCs are associated with loss of BRCA1 and 34.5% with the loss of BRCA2 expression.

CONCLUSION

IHC was effective to detect loss of BRCA1 protein expression in EOC; however, data on BRCA2 expression were heterogeneous and difficult to interpret.

Expression of breast cancer type 1 and its relation with expression of estrogen receptors, progesterone receptors, and human epidermal growth factor receptor 2/neu in breast carcinoma on trucut biopsy specimens

Objective

(1) The objective is to study the immunohistochemical expression of Breast cancer type 1 (BRCA1) in breast carcinoma on trucut biopsy specimens and (2) To relate its expression with that of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER-2)/neu and the clinicopathological parameters.

Settings and Design

A cross-sectional hospital-based study was performed in Lady Hardinge Medical College and Shrimati Sucheta Kriplani Hospital, New Delhi, with collaboration of the Departments of Pathology and Surgery from the period of November 2008 to March 2010.

Materials and Methods

The study group included 54 cytologically proven cases of breast carcinoma. The immunohistochemical expression of BRCA1 was studied and related with expression of ER, PR, and HER-2/neu on their trucut biopsies.

Results

The altered expression of BRCA1 (i.e., reduced or absent expression) was seen in 44.4% cases of breast carcinoma while 55.6% had positive expression. About 83% of breast carcinomas with altered BRCA1 expression were larger than 3 cm in size. The breast carcinomas showing altered expression were found to be mostly high grade (63.6%). This was statistically significant. The ER and PR negativity were seen in 62.5% and 79.2% breast carcinomas with altered BRCA1 expression, respectively. The score 3 positivity of HER-2/neu was more common among carcinomas with altered BRCA1 expression (21% vs. 16.7%). The triple negativity was found in 41.7% breast carcinomas having altered BRCA1 expression. This was statistically significant.

Conclusion

The combination of immunohistochemical expression of BRCA1, ER, PR, and HER-2/neu and clinicopathological details may be helpful in predicting the individuals more likely to carry BRCA1 mutations and thus selecting the candidate and family members for genetic screening for BRCA1 mutations.

BRCA1/2 Mutations in Salivary Pleomorphic Adenoma and Carcinoma-ex-Pleomorphic Adenoma

Objectives:

It is hypothesized that carcinoma-ex-pleomorphic adenoma (Ca-ex-PA) is malignant from the beginning or is a malignant transformation of a recurrent or a long-standing pleomorphic adenoma (PA). The accumulation of genetic instabilities is suggested to be the main reason for malignant transformation in PA. The aim of this study was to determine the prevalence of BRCA1/2 mutations in PA and Ca-ex-PA.

Materials and Methods:

A total of ninety salivary gland tumors (45 Ca ex-PA and 45 PA) were selected. Immunohistochemistry was performed for all samples. Analyses were conducted through SPSS software version 22.0 (SPSS, Inc., Chicago, IL, USA). Chi-square test was used to examine the differences between the variables. Significant level was set at 0.05.

Results:

In general, 93.3% of PA samples showed positive staining for BRCA1 (in myoepithelial cells); however, BRCA2 positivity was found in 60% of samples (in myoepithelial cells). Among 45 samples of Ca-ex-PA, 93.3% of showed positivity for BRCA1 and 80% of samples showed positivity for BRCA2. Chi-square test found differences between PAs and Ca-ex-PAs regarding BRCA1/2 mutations in ductal cells and myoepithelial cells (P = 0.007, 0.000), respectively.

Conclusions:

The present study found a trend toward the presence of BRCA1/2 mutations in PA and Ca-ex-PA samples. Patients with BRCA1/2 mutation carriers are excellent cases for therapies, such as the poly (ADP) ribose polymerase inhibitor.

Cancer heterogeneity determined by functional proteomics

Current manuscript gives a synopsis of tumor heterogeneity related to patient samples analyzed by proteomics, protein expression analysis and imaging mass spectrometry. First, we discuss the pathophysiologocal background of cancer biology as a multifactorial and challenging diseases. Disease pathology forms the basis for protein target selection. Therefore, histopathological diagnostics and grading of tumors is highlighted. Pathology is the cornerstone of state-of-the-art diagnostics of tumors today both by establishing dignity and - when needed - describing molecular properties of the cancers. Drug development by the pharmaceutical industry utilizes proteomics studies to pinpoint the most relevant targets. Molecular studies profiling affinity-interactions of the protein(s) with targeted small drug molecules to reach efficacy and optimal patient safety are today requested by the FDA and other agencies for new drug development. An understading of basic mechanisms, controlling drug action and drug binding is central, as a new era of personalized medicine becomes an important milestone solution for the healthcare sector as well as the Pharma and Biotech industry. Development of further diagnostic, prognostic and predictive tests will aid current and future treatment of cancer patients. In the paper we present current status of Proteomics that we believe requires attention in order to collectively advance forward in the fight against cancer, addressing the burning opportunities and challenges.

Evaluation of the methods to identify patients who may benefit from PARP inhibitor use

The effectiveness of poly (ADP-ribose) polymerase inhibitors (PARPi) in treating cancers associated with BRCA1/2 mutations hinges upon the concept of synthetic lethality and exemplifies the principles of precision medicine. Currently, most clinical trials are recruiting patients based on pathological subtypes or have included BRCA mutation analysis (germ line and/or somatic) as part of the selection criteria. Mounting evidence, however, suggests that these drugs may also be efficacious in tumors with defects in other genes involved in the homologous recombination repair pathway. Advances in molecular profiling techniques together with increased research efforts have led to a better understanding of the molecular aberrations underlying this BRCA-like phenotype and helped broaden the concept of BRCAness. Hence, it is likely that the list of predictive biomarkers for PARPi therapy will increase in future. There is currently no gold standard method of testing for PARPi response and no universal guidelines are in place on how to incorporate biomarker testing into routine clinical diagnostics. In this review, we explore the concept of BRCAness and highlight the different methods that have been used to identify patients who may benefit from the use of these anticancer agents. The identification of predictive biomarkers is crucial in improving patient selection and expanding the clinical applications of PARPi therapy.

Identification of novel BRCA founder mutations in Middle Eastern breast cancer patients using capture and Sanger sequencing analysis

Ethnic differences of breast cancer genomics have prompted us to investigate the spectra of BRCA1 and BRCA2 mutations in different populations. The prevalence and effect of BRCA 1 and BRCA 2 mutations in Middle Eastern population is not fully explored. To characterize the prevalence of BRCA mutations in Middle Eastern breast cancer patients, BRCA mutation screening was performed in 818 unselected breast cancer patients using Capture and/or Sanger sequencing. 19 short tandem repeat (STR) markers were used for founder mutation analysis. In our study, nine different types of deleterious mutation were identified in 28 (3.4%) cases, 25 (89.3%) cases in BRCA 1 and 3 (10.7%) cases in BRCA 2. Seven recurrent mutations identified accounted for 92.9% (26/28) of all the mutant cases. Haplotype analysis was performed to confirm c.1140 dupG and c.4136_4137delCT mutations as novel putative founder mutation, accounting for 46.4% (13/28) of all BRCA mutant cases and 1.6% (13/818) of all the breast cancer cases, respectively. Moreover, BRCA 1 mutation was significantly associated with BRCA 1 protein expression loss (p = 0.0005). Our finding revealed that a substantial number of BRCA mutations were identified in clinically high risk breast cancer from Middle East region. Identification of the mutation spectrum, prevalence and founder effect in Middle Eastern population facilitates genetic counseling, risk assessment and development of cost‐effective screening strategy.

What's new?

Genetic testing for BRCA mutations reveals the ethnic diversity of prevalence and spectrum of BRCA1/BRCA2 mutations in breast cancer. Compared with other populations, however, little is known about ethnic differences in breast cancer genomics in populations in the Middle East region. Here, BRCA mutation screening was carried out in 818 Middle Eastern breast cancer patients. The authors identify two putative founder mutations—together accounting for more than 46% of BRCA cases—and a particular spectrum of deleterious BRCA mutations, which may be unique to the population. The findings could impact genetic counseling in Middle Eastern populations.

The performance of BRCA1 immunohistochemistry for detecting germline, somatic, and epigenetic BRCA1 loss in high-grade serous ovarian cancer

BACKGROUND

BRCA1 expression can be lost by a variety of mechanisms including germline or somatic mutation and promotor hypermethylation. Given the potential importance of BRCA1 loss as a predictive and prognostic biomarker in high-grade serous ovarian cancer, we sought to evaluate the utility of BRCA1 immunohistochemistry (IHC) in screening for BRCA1 loss by germline, somatic, and epigenetic mechanisms.

PATIENTS AND METHODS

Patients with advanced high-grade serous ovarian cancer who had previously undergone germline BRCA1 testing were identified. Samples from each tumor were stained for BRCA1 and reviewed independently by two pathologists blinded to BRCA status. Tumors with abnormal BRCA1 IHC and wild-type germline testing underwent further evaluation for somatic BRCA1 mutations and promoter hypermethylation. McNemar's test was used to determine the association of BRCA1 IHC with germline BRCA1 mutations and BRCA1 loss through any mechanism. Kaplan-Meier methods were used to estimate overall survival (OS), and the log-rank test was used to assess differences between groups.

RESULTS

Inter-rater reliability between the two pathologists on BRCA IHC interpretation was very good (kappa coefficient 0.865, P = 0.16; McNemar's test). BRCA1 IHC was abnormal in 36% (48/135) of cases. When compared with germline BRCA1 status, BRCA1 IHC had a high negative predictive value (95.4%) but a low positive predictive value (PPV, 52.1%). When accounting for promoter hypermethylation and somatic mutations as alternative methods of BRCA1 loss, the PPV rose to 87.5%. Five-year OS rate was 49.6% [95% confidence interval (CI) 26.3% to 69.3%] for patients with germline BRCA1 mutations, 50.4% (95% CI 27.5% to 69.5%) for germline wild-type BRCA1 and abnormal IHC, and 52.1% (95% CI 38.4% to 64.2%) for germline wild-type BRCA1 and normal IHC (P = 0.92).

CONCLUSIONS

BRCA1 IHC interpretation was a highly reproducible and accurate modality for detecting germline, somatic, or epigenetic mechanisms of BRCA1 loss. These results support further development of BRCA1 IHC as a potential biomarker for BRCA1 loss in high-grade serous ovarian cancer.

BRCA1/2 germline mutations and their clinical importance in Turkish breast cancer patients

BRCA1/BRCA2 genes were screened in 117 patients with breast cancer by sequencing. Fourteen percent of patients tested positive for BRCA1/BRCA2 mutations. Four frame shift mutations, four pathogenic missense mutations, and 25 different sequence variations were detected. BRCA mutation positivity was significantly associated with Ki67 (p = .001). BRCA protein expressions were decreased in the patients harboring important mutations and polymorphisms (BRCA1;P508 stop, V1740G, Q1182R, Q1756P and BRCA2;V2466A) related with disease. Our findings contribute significantly to the types of germline BRCA1/BRCA2 mutations and their biological effects in Turkish women. These data could help guide the management of BRCA1/BRCA2 mutation-carrying patients when considering breast-conserving therapy.

BRCA1 immunohistochemistry in a molecularly characterized cohort of ovarian high-grade serous carcinomas

BRCA1 and BRCA2 dysfunction, frequently seen in high-grade serous ovarian carcinomas, often results from germline mutations, somatic mutations, and promoter methylation. Identification of tumors with BRCA defects has therapeutic and prognostic implications. Identifying germline BRCA mutations is also important given the increased risk for hereditary breast and ovarian carcinoma. Our goal was to assess whether immunohistochemical analysis (IHC) for BRCA1 is an effective method for the detection of BRCA1 dysfunction in molecularly characterized high-grade ovarian serous carcinoma. We identified 43 high-grade ovarian serous carcinomas with known events in BRCA1 and BRCA2 included in The Cancer Genome Atlas Project. BRCA1 stain was first assessed without knowledge of the BRCA status, and a semiquantitative assessment for intensity and amount of staining was performed. The stains were reevaluated and divided into 3 categories (retained, loss, and equivocal) on the basis of correlation with genotyping data. Presence of retained BRCA staining was considered normal, whereas the other patterns, including equivocal staining or loss of staining, were considered abnormal. Two pathologists, blinded to the BRCA status, then scored 2 sets of validation cases selected on the basis of available molecular data-1 with only germline mutation status available (n=31) and 1 with comprehensive genomic data (n=39). The pathologists agreed 88% of the time in the training set and 91% in the validation sets. In the training set, abnormal BRCA staining was seen in 24 cases, of which 21 (87%) showed BRCA1 genetic abnormalities, 1 showed BRCA2 mutations, and 2 showed no BRCA abnormalities. Abnormal BRCA1 staining was noted in all 5 cases with BRCA1 germline mutations, in 3 (60%) of 5 with BRCA1 somatic mutations, and in 13 (93%) of 14 with BRCA1 promoter methylation. The 2 validation sets included 70 additional patients, and all cases with germline BRCA1 mutations (n=11) showed abnormal BRCA1 staining. Tumors with BRCA1 promoter methylation also showed abnormal staining in 6 (86%) of 7 cases. In the entire study, no cases with BRCA1 germline mutation showed intact immunostaining (negative predictive value=100%). This study shows that BRCA1 IHC is well correlated with molecular events in ovarian carcinoma. Considering the high negative predictive value for germline mutations, BRCA1 IHC appears to be an effective approach to stratify patients for germline genetic testing and to detect other mechanisms of BRCA1 dysfunction in high-grade serous ovarian carcinomas.

Detecting BRCA2 protein truncation in tissue biopsies to identify breast cancers that arise in BRCA2 gene mutation carriers

PURPOSE

Mutations in the BRCA2 gene are dominantly inherited but cause cancers when the wild-type allele has loss of heterozygosity (LOH) within the cancer. Because most disease-associated BRCA2 mutations are protein-truncating mutations, a test for truncated BRCA2 proteins should identify most BRCA2 hereditary cancers.

METHODS

We have developed a tissue truncation test to identify truncated BRCA2 proteins in breast cancer tissue biopsies in vivo that does not use amplification or genetic manipulations. N-terminal and C-terminal antibodies are used to visualize protein truncation by demonstrating that the beginning of the protein is present but the end (ie, terminus) is absent.

RESULTS

A quantitative C-terminal immunostaining score or a C-terminal to N-terminal truncation ratio correctly classified 20 of 21 breast cancers arising in BRCA2 mutation carriers and 57 of 58 cancers arising outside the context of a multiple-case breast cancer family. This represents a sensitivity of 95% and a specificity of 98%. Because of the presence of C-terminal BRCA2 protein and atypical clinical features of the misclassified cancer in a BRCA2 mutation carrier, we performed polymerase chain reaction and sequence analyses on this cancer. The results showed continued presence of the BRCA2 wild-type allele in the cancer, which indicated that intact BRCA2 protein was present in this cancer.

CONCLUSION

This immunohistochemistry-based test (which takes only 4 hours) appears to identify BRCA2 hereditary cancer with high accuracy. The test also appears to diagnose the biochemical loss of BRCA2 protein in cancers (ie, BRCA2-mutant genotype), which will usually but not always agree with the presence of a germline BRCA2 mutation found by susceptibility testing by DNA sequencing of blood samples.

Clinicopathological study of male breast carcinoma: 24 years of experience

BACKGROUND AND OBJECTIVES

Because breast cancer in men is rare, few patients are available for prospective studies. To learn more about its epidemiology, risk factors, clinical features, genetics and pathology in our country, we conducted a retrospective study of all cases seen in recent decades at our institution.

PATIENTS AND METHODS

We identified each case of male breast cancer in the database at the Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Kashmir, India, between the years 1983 to 2007.

RESULTS

We identified only 32 cases of male breast cancer over the 24-year period. Male breast cancer accounted for 32 (2.8%) of 1141 resected breast specimens, which included all breast lesions and 32 (4.1%) of 780 breast cancer cases. Of the 32 cases, 20 (62.5%) had various associated risk factors. Invasive ductal carcinoma was seen in 30 cases (93.7%). Of 20 cases that underwent molecular studies, 16 (80%) patients had estrogen receptor positivity whereas 14 (70%) had progesterone receptor positivity. Six cases (30%) overexpressed HER2 and p53. The BRCA2 mutation was observed in 4 cases (40%) while no patient presented with the BRCA1 mutation.

CONCLUSION

An incidence of 4.1% for male breast cancer indicates that this disease is not as uncommon as presumed in this part of the world. Breast cancer in men seems more frequently to be hormone receptor positive and the BRCA2 mutation confers a significant risk to men.

Familial breast/ovarian cancer and BRCA1/2 genetic screening: the role of immunohistochemistry as an additional method in the selection of patients

Only 20-25% of families screened for BRCA1/2 mutations are found positive. Because only a positive result is informative, we studied the role of BRCA1/2 immunohistochemistry as an additional method for patient selection. From 53 high-risk-affected probands, 18 (34%) had available paraffin blocks of their tumors and were selected for this study. Mutation screening was done by conformation-sensitive gel electrophoresis and multiplex ligation-dependent probe amplification. For immunohistochemistry, 21 neoplastic specimens (15 breast carcinomas, 5 ovary neoplasms, and 1 rectal adenocarcinoma) were analyzed with BRCA1 (monoclonal antibody, Ab-1, oncogene) and BRCA2 (polyclonal antibody, Ab-2, oncogene) antibodies. Absence of the BRCA1 protein was confirmed in negative tumors by Western blotting. Seven patients were positive for BRCA1/2 mutations: 5 for BRCA1 and 2 for BRCA2. Four out of five positive patients had tumors negative for BRCA1 immunostaining, and the remaining 13 BRCA1-negative patients had positive BRCA1 immunostaining in all tumor samples. Sensitivity to predict for BRCA1 mutation carriers was 80%, and specificity was 100%, with a positive predictive value of 100% and a negative predictive value of 93%. This correlation was statistically significant (p=0.001). No correlation was observed for BRCA2. If larger studies confirm these results, high-risk patients with BRCA1-negative tumors should be screened first for this gene.