Morphology of Breast Cancer as a Means of Triage of Patients for BRCA1 Genetic Testing

Predicting the Likelihood of Carrying a BRCA1 or BRCA2 Mutation in Asian Patients With Breast Cancer

PURPOSE

With the development of poly (ADP-ribose) polymerase inhibitors for treatment of patients with cancer with an altered BRCA1 or BRCA2 gene, there is an urgent need to ensure that there are appropriate strategies for identifying mutation carriers while balancing the increased demand for and cost of cancer genetics services. To date, the majority of mutation prediction tools have been developed in women of European descent where the age and cancer-subtype distributions are different from that in Asian women.

METHODS

In this study, we built a new model (Asian Risk Calculator) for estimating the likelihood of carrying a pathogenic variant in BRCA1 or BRCA2 gene, using germline BRCA genetic testing results in a cross-sectional population-based study of 8,162 Asian patients with breast cancer. We compared the model performance to existing mutation prediction models. The models were evaluated for discrimination and calibration.

RESULTS

Asian Risk Calculator included age of diagnosis, ethnicity, bilateral breast cancer, tumor biomarkers, and family history of breast cancer or ovarian cancer as predictors. The inclusion of tumor grade improved significantly the model performance. The full model was calibrated (Hosmer-Lemeshow P value = .614) and discriminated well between BRCA and non-BRCA pathogenic variant carriers (area under receiver operating curve, 0.80; 95% CI, 0.75 to 0.84). Addition of grade to the existing clinical genetic testing criteria targeting patients with breast cancer age younger than 45 years reduced the proportion of patients referred for genetic counseling and testing from 37% to 33% (P value = .003), thereby improving the overall efficacy.

CONCLUSION

Population-specific customization of mutation prediction models and clinical genetic testing criteria improved the accuracy of BRCA mutation prediction in Asian patients.

Loss of BRCA1 expression and morphological features associated with BRCA1 promoter methylation status in triple-negative breast cancer

Aberrant DNA methylation in the BRCA1 promoter region causes epigenetic silencing of BRCA1 gene expression, which is critical for breast cancer development. However, how BRCA1 promoter methylation status alters histological features remains poorly understood. Here, we investigated the possibility to predict BRCA1 promoter methylation status based on the morphological and immunohistochemical features of triple-negative breast cancers (TNBCs). The morphological features of 53 TNBCs were evaluated with hematoxylin-eosin staining, with immunohistochemical staining of BRCA1, androgen receptor, p53, cytokeratin 5/6, and epidermal growth factor receptor. BRCA1 promoter methylation status was used to distinguish BRCA1 promoter-methylated tumors (BPMTs) from BRCA1 promoter-unmethylated tumors (BPUTs) dependent on pathological characteristics. BPMTs comprised approximately 26% of the TNBCs. Immunohistochemical analysis found that BRCA1 protein expression was significantly lower in BPMT compared with BPUT (p = 0.016). Morphologically, BPMTs were associated with high mitotic index (p = 0.017), pushing margin (p = 0.017), a circumscribed growth pattern (p = 0.014), and a syncytial growth pattern (p = 0.034) compared with BPUTs. We then assessed the potential of predicting BRCA1 promoter methylation status by using published score systems based on these morphological characteristics. A receiver operating characteristic analysis showed an area under the curve of 0.80. This study found that BRCA1 promoter methylation status could be derived from morphological features and lower BRCA1 expression of TNBCs, which may help identify suitable cases for target treatment with PARP inhibitors.

The molecular basis of breast cancer pathological phenotypes

The histopathological evaluation of morphological features in breast tumours provides prognostic information to guide therapy. Adjunct molecular analyses provide further diagnostic, prognostic and predictive information. However, there is limited knowledge of the molecular basis of morphological phenotypes in invasive breast cancer. This study integrated genomic, transcriptomic and protein data to provide a comprehensive molecular profiling of morphological features in breast cancer. Fifteen pathologists assessed 850 invasive breast cancer cases from The Cancer Genome Atlas (TCGA). Morphological features were significantly associated with genomic alteration, DNA methylation subtype, PAM50 and microRNA subtypes, proliferation scores, gene expression and/or reverse-phase protein assay subtype. Marked nuclear pleomorphism, necrosis, inflammation and a high mitotic count were associated with the basal-like subtype, and had a similar molecular basis. Omics-based signatures were constructed to predict morphological features. The association of morphology transcriptome signatures with overall survival in oestrogen receptor (ER)-positive and ER-negative breast cancer was first assessed by use of the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) dataset; signatures that remained prognostic in the METABRIC multivariate analysis were further evaluated in five additional datasets. The transcriptomic signature of poorly differentiated epithelial tubules was prognostic in ER-positive breast cancer. No signature was prognostic in ER-negative breast cancer. This study provided new insights into the molecular basis of breast cancer morphological phenotypes. The integration of morphological with molecular data has the potential to refine breast cancer classification, predict response to therapy, enhance our understanding of breast cancer biology, and improve clinical management. This work is publicly accessible at www.dx.ai/tcga_breast. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Detection of Human Papillomavirus Genotypes and Major BRCA Mutations in Familial Breast Cancer

Breast cancer is a multistep disease and infection with a DNA virus could play a role in one or more of the steps in this pathogenic process. High-risk human papillomaviruses (HPVs) are the causative agents of several cancers. In this study, we investigated HPV genotypes associated with breast cancer and its relationship with BRCA mutation for the detection of familial breast cancer. We analyzed 84 formalin-fixed, paraffin-embedded tissue blocks from 38 familial breast cancer and 46 nonfamilial breast cancer samples by multiplex polymerase chain reaction and clinical parameters. Overall prevalence of HPV infection was 27 of 84: 10 (37.03%) HPV-16, 9 (29.62%) HPV-18, 4 (14.81%) HPV-11, 1 (3.7%) HPV-31, 1 (3.7%) HPV-33, and 2 (7.4%) HPV35. Furthermore, 17 mtDNA4977 deletions and 5 5382insC mutations were detected from 38 familial breast cancer samples. Our results demonstrate that infection with HPV was prevalent among Iranian women with familial breast cancer and the testing of mtDNA4977 deletions and 5382insC mutations in combination with clinical parameters as major risk factors can serve in the identification of familial breast cancer.

BRCA-mutated Invasive Breast Carcinomas: Immunohistochemical Analysis of Insulin-like Growth Factor II mRNA-binding Protein (IMP3), Cytokeratin 8/18, and Cytokeratin 14

To evaluate the expression of insulin-like growth factor II mRNA-binding protein (IMP3), CK8/18, and CK14 in BRCA mutated and sporadic invasive breast carcinoma. Immunohistochemistry for IMP3, CK8/18, and CK14 was performed on 39 cases of invasive breast carcinomas with BRCA mutation (24 BRCA1, 14 BRCA2, and 1 dual BRCA1/BRCA2) and 54 cases of sporadic invasive breast carcinomas. The relationship between the IMP3, CK8/18, and CK14 and the tumor grade and molecular phenotypes were analyzed. IMP3, CK8/18, and CK14 positivity were present in 20 (51%), 22 (56%), and 14 (36%) of 39 BRCA-mutated breast carcinomas, and 11 (20%), 53 (98%), and 24 (44%) of 54 sporadic breast carcinomas respectively. The rates of IMP3 expression and absence of CK8/18 (44% versus 2%) in BRCA-mutated breast carcinomas was significantly higher than the sporadic breast carcinomas (p = 0.002 and p < 0.001). No significant difference was observed for CK14 among the two groups (p = 0.408). No significant difference was observed among BRCA1-related and BRCA2-related breast carcinomas in the immunoprofile for IMP3, CK8/18, and CK14. No significant correlation was identified between the expression of IMP3 and CK8/18 and the tumor grade in both BRCA-mutated and sporadic breast carcinomas (p > 0.05). In cases with luminal A and B phenotypes, the rates of expression of IMP3 and loss of CK8/18 were significantly higher in BRCA-mutated as compared to sporadic breast carcinoma (p < 0.001). In cases with basal-like phenotype, the absence of CK8/18 expression was significantly higher in BRCA-mutated breast carcinomas (54% versus 0%, p = 0.001), while no difference was observed for IMP3 expression (p = 0.435). Regardless of mutation type, histologic grade, or molecular phenotype, the absence of CK8/18 expression and presence of IMP3 expression are seen at much higher rate in BRCA mutated breast carcinomas.

Genotype/Phenotype correlations in patients with hereditary breast cancer

Of all breast cancer cases, 5-10% can be attributed to germline mutations, and the high-susceptibility genes BRCA1 and BRCA2 account for about 25-28% of these cases. For the remainder, several genes of moderate and low penetrance have been discovered. Histopathologic characteristics have been studied in small cohorts, but for most of the known non-BRCA1/2-associated hereditary breast cancers, the histologic and immunohistochemical phenotypes are not yet identified. Particularly BRCA1 tumors are associated with a distinct morphology and immunohistochemical characteristics that differ from sporadic breast cancer of age-matched controls. The recognition of features characteristic of these mutations can be helpful to identify patients likely to carry a germline mutation and to assess which gene should be screened for first, in families with a high occurrence of breast and ovarian cancer.

Lobulitis in nonneoplastic breast tissue from breast cancer patients: association with phenotypes that are common in hereditary breast cancer

Lobular inflammation (lobulitis) has been demonstrated in benign breast tissue adjacent to in situ and invasive breast cancers and, more recently, in nonneoplastic tissue from prophylactic mastectomy specimens for hereditary high-risk breast carcinoma. The aim of this study is to investigate the incidence of lobulitis in benign breast tissue of patients with breast cancer and associated clinicopathologic features. We reviewed nonneoplastic breast tissue sections from 334 patients with invasive breast carcinoma to study lobulitis in normal breast tissue and to correlate its presence with clinicopathologic features of the associated tumor. Clinical information (age, menopausal status, and follow-up), tumor characteristics (type, grade, size, lymph node status, stage, estrogen and progesterone receptor, HER2), and survival were recorded. Characteristics of women with and without lobulitis were cross-classified with categories of clinical, pathologic, and histologic characteristics, and differences in distributions were tested in univariate and multivariate analysis. Lobulitis was found in 26 (8%) of 334 patients. The lymphocytic infiltrate was predominantly T-cell type. In a multivariate model, lobulitis in patients with breast cancer was significantly associated with younger age, triple (estrogen receptor, progesterone receptor, HER2)-negative cancers, and medullary phenotypes. Lobulitis in nonneoplastic breast tissue, away from tumor, is associated with clinicopathologic features more commonly seen in hereditary breast cancer.

The complex genetic landscape of familial breast cancer

Familial breast cancer represents a minor percentage of all human breast cancers. Mutations in two high susceptibility genes BRCA1 and BRCA2 explain around 25 % of familial breast cancers, while other high, moderate and low susceptibility genes explain up to 20 % more of breast cancer families. Thus, it is important to decipher the genetic architecture of families that show no mutations to improve genetic counselling. The comprehensive description of familial breast cancer using different techniques and platforms has shown to be very valuable for better patient diagnosis, tumour surveillance, and ultimately patient treatment. This review focuses on the complex landscape of pathological, protein, genetic and genomic features associated with BRCA1-, BRCA2-, and non-BRCA1/BRCA2-related cancers described up to date. Special emphasis deserves the coexistence of distinct molecular breast cancer subtypes, the development of tumour classifiers to predict BRCA1/2 mutations, and the last insights from recent whole genome sequencing studies and miRNA profiling.

Prediction of BRCA1 germline mutation status in women with ovarian cancer using morphology-based criteria: identification of a BRCA1 ovarian cancer phenotype

Specific morphologic features that may predict BRCA1 germline mutation in ovarian cancer have neither been well described nor independently tested. We identified 5 morphologic features associated with BRCA1 mutation status in a series of 20 ovarian cancers from BRCA1 mutation carriers: (1) modified Nottingham grade 3; (2) serous/undifferentiated histology; (3) prominent intraepithelial lymphocytes; (4) marked nuclear atypia with giant/bizarre forms; and (5) abundant mitotic figures. These morphologic features were then tested on 325 ovarian tumors drawn from a population-based Greater Bay Area Cancer Registry and classified into 3 categories independent of the BRCA1 status: "Compatible with BRCA1," "Possibly compatible with BRCA1," and "Not compatible with BRCA1." All "Compatible with BRCA1" tumors were additionally investigated for presence of dominant adnexal mass, fallopian tube mucosal involvement, and uterine cornu involvement. The positive and negative predictive values for "Compatible with BRCA1" were 11/42 (26.2%) and 267/283 (94.3%), respectively, whereas combining the "Compatible with BRCA1" and "Possibly compatible with BRCA1" had positive and negative predictive values of 18/85 (21.2%) and 231/240 (96.3%), respectively. Although dominant adnexal mass and uterine cornu involvement did not add further predictive value, the likelihood of BRCA1 positivity increased to 42.9% when a tumor with "Compatible with BRCA1" histology was also associated with fallopian tube mucosal involvement. The combination of modified Nottingham grade 3 serous or undifferentiated histology, prominent intraepithelial lymphocytes, marked nuclear atypia with giant/bizarre nuclei, and high mitotic index should help to identify women for BRCA1 mutational analysis in the appropriate clinical setting. Ovarian tumors lacking this specific phenotype are unlikely to be associated with BRCA1 and should not undergo mutational analysis in the absence of other indications.

Phenotype-genotype correlation in familial breast cancer

Familial breast cancer accounts for a small but significant proportion of breast cancer cases worldwide. Identification of the candidate genes is always challenging specifically in patients with little or no family history. Therefore, a multidisciplinary team is required for the proper detection and further management of these patients. Pathologists have played a pivotal role in the cataloguing of genotypic-phenotypic correlations in families with hereditary cancer syndromes. These efforts have led to the identification of histological and phenotypic characteristics that can help predict the presence or absence of germline mutations of specific cancer predisposition genes. However, the panoply of cancer phenotypes associated with mutations of genes other than in BRCA1 is yet to be fully characterised; in fact, many cancer syndromes, germline mutations and gene sequence variants are under investigation for their possible morphological associations. Here we review the current understanding of phenotype-genotype correlation in familial breast cancer.

The contribution of breast cancer pathology to statistical models to predict mutation risk in BRCA carriers

BRCA1 and BRCA2 associated breast cancer comprises a small but important group of hereditary breast cancer. Testing for BRCA1 and BRCA2 has significant clinical and personal implications for the patients in terms of therapy and follow-up of individual family members. The sequencing of the genes is expensive and since the information derived may have a profound effect on the individual and family members, it is important that testing is done only when the risk of carrying a mutation is thought to be high. Over the last decade, researchers have developed a number of statistical models for predicting risk for harboring mutations in these genes and the risk of subsequently developing breast and ovarian cancer. These models usually take into account the type of tumor and age at occurrence as well as family history. Data from pathological analysis show that although breast tumours are heterogeneous, there are histological characteristics that are seen more frequently in carriers of BRCA1 germ line mutations compared to BRCA2 and sporadic breast cancers. A number of authors have suggested that the addition of pathological data to risk algorithms may improve the predictive power of these models and provide a more accurate way of identifying individuals who may benefit from testing. Here we review the pathology of familial breast cancer and assess the evidence to justify the use of pathology in refining risk assessment models.

Molecular testing of solid tumors

CONTEXT

Molecular testing of solid tumors is steadily becoming a vital component of the contemporary anatomic pathologist's armamentarium. These sensitive and specific ancillary tools are useful for confirming ambiguous diagnoses suspected by light microscopy and for guiding therapeutic decisions, assessing prognosis, and monitoring patients for residual neoplastic disease after therapy.

OBJECTIVE

To review current molecular biomarkers and tumor-specific assays most useful in solid tumor testing, specifically of breast, colon, lung, thyroid, and soft tissue tumors, malignant melanoma, and tumors of unknown origin. A few upcoming molecular diagnostic assays that may become standard of care in the near future will also be discussed.

DATA SOURCES

Original research articles, review articles, and the authors' personal practice experience.

CONCLUSIONS

Molecular testing in anatomic pathology is firmly established and will continue to gain ground as the need for more specific diagnoses and new targeted therapies evolve. Knowledge of the more common and clinically relevant molecular tests available for solid tumor diagnosis and management, and their indications and limitations, is necessary if anatomic pathologists are to optimally use these tests and act as consultants for fellow clinicians directly involved in patient care.

CK8/18 expression, the basal phenotype, and family history in identifying BRCA1-associated breast cancer in the Ontario site of the breast cancer family registry

BACKGROUND

BRCA1-associated breast cancer had been shown to be morphologically and genetically distinct from sporadic cancers. The aim of this study was to determine the association of CK8/18 with BRCA1-associated tumors and if, by using CK8/18 and basal biomarkers in conjunction with morphologic features and family history characteristics, the specificity of the BRCA1-associated tumor profile in a pathologically well-characterized cohort would be improved.

METHODS

Fifty-eight patients with known BRCA1 germline mutations and 221 control (familial non-BRCA) patients were selected from the Ontario Familial Breast Cancer Registry. From this database, information on family history and morphologic features was abstracted. Tissue microarrays were constructed and immunohistochemistry to determine expression of several biomarkers was performed. After a logistic regression fit, a best-subsets variable-selection procedure using model performance and predictive ability measures was applied to find a best predictor to distinguish BRCA1-associated tumors from non-BRCA associated tumors.

RESULTS

BRCA1-associated tumors differed significantly from control tumors in terms of morphology, family history, and biomarker profile. CK8/18 was highly significantly associated with BRCA1 tumors. Consistently, BRCA1 cancers showed low levels of CK8/18 compared to non-BRCA tumors, whether they were basal-like or not. A combination of 7 factors, including CK8/18 and family history, best predicted the BRCA1-associated cancers.

CONCLUSIONS

CK8/18 expression was independently associated with BRCA1-associated breast cancers. Reduced CK8/18 expression in conjunction with the basal-like phenotype and family history may have improved the ability to identify which tumors were likely to be associated with a BRCA1 germline mutation and thereby help streamline genetic testing.

Pathology of hereditary breast cancer

Patients with germline mutations in BRCA1 or BRCA2 genes are predisposed to breast cancer. The BRCA1-associated breast cancers have distinct morphology, being more often medullary-like, triple negative and showing a 'basal' phenotype. On the other hand, BRCA2 and BRCAX cancers are a heterogeneous group without a specific phenotype. When incorporated into risk assessment models, pathology data improves prediction of carrier status. The role of BRCA1 and BRCA2 in DNA repair is being exploited to develop novel therapies, for example, using the poly-ADP-ribose polymerase inhibitors. A number of low-to-moderate-penetrant genes/loci have also been identified, but their role and contribution in breast cancer development is still under investigation.

Basal cytokeratin and epidermal growth factor receptor expression are not predictive of BRCA1 mutation status in women with triple-negative breast cancers

BACKGROUND

Over 80% of breast cancers in women with germline BRCA1 mutations are estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2-negative ("triple negative") and most of these have a basal-like phenotype by expression profiling and immunophenotypic analysis. However, whether or not expression of biomarkers characteristic of basal-like breast cancers helps to define a subset of women with triple-negative breast cancers who are likely to harbor BRCA1 mutations is an unresolved issue.

METHODS

We randomly identified 165 women from the Dana-Farber/Harvard Cancer Center SPORE annotated specimen bank with primary invasive, triple-negative breast cancers. Tissue microarrays were constructed by obtaining triplicate 0.6 mm cores from available paraffin blocks from 130 cases: only unstained slides were available for immunostaining from 35 cases. Slides cut from the tissue microarrays and the unstained slides were immunostained for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (to confirm triple-negative status) and for several markers that have been reported to be useful in defining the basal-like phenotype, including basal cytokeratins CK5/6, CK14, and CK17 and epidermal growth factor receptor (EGFR). Full sequencing analysis for BRCA1 germline mutations was performed on blood specimens from all cases. The final study population consisted of 144 cases in which (1) triple-negative status was confirmed; (2) there was sufficient material for analysis of basal cytokeratins and EGFR; and (3) germline BRCA1 mutation status was known.

RESULTS

Among these triple-negative breast cancer cases, 97 (67%) expressed one or more basal cytokeratins and 102 (71%) showed EGFR expression. Basal cytokeratin expression was detected in 65% of the tumor from the 20 BRCA1 mutation carriers and in 68% of the cancers from women without mutations (P=NS). EGFR expression was identified in a similar proportion of tumors from women with and without BRCA1 mutations (75% vs. 72%, P=NS).

CONCLUSIONS

Basal cytokeratin and EGFR expression are both highly prevalent among triple-negative breast cancers. The frequency of expression of basal cytokeratins and EGFR was similar in women with and without BRCA1 mutations. Therefore, although the expression of basal cytokeratins and/or EGFR can be used to identify triple-negative breast cancers that have a basal-like phenotype, expression of these markers alone is not sufficient to distinguish which women with triple-negative breast cancers are likely to harbor BRCA1 germline mutations.

BRCA1/2 mutations and triple negative breast cancers

Identifying breast cancer patients at increased risk for carrying a mutation in the BRCA1 and BRCA2 genes is an important objective in clinical practice. Although age at diagnosis, family history of breast and/or ovarian cancer, and ethnicity are all essential parameters to consider when assessing risk, there are limitations as to how well such factors accurately predict BRCA1/2 status, even when quantitative risk models are applied. Integrating information about triple negative (TN) disease may help refine these estimates. Among newly diagnosed breast cancer patients, fewer than 10% have a mutation in the BRCA1 or BRCA2 genes, and up to 20% present However, among BRCA1 mutation carriers at least one-third have TN breast cancers. In this paper, we review key studies that have assessed breast cancer cases with a known BRCA1/2 status and triple marker data. We also discuss how integrating such information into qualitative and quantitative risk assessments of BRCA1/2 carrier probability may improve the ability to identify women who are appropriate candidates for genetic testing. Identifying women at increased risk is critical as knowledge of mutation status may impact surgical and systemic treatment in newly diagnosed patients, as well as recommendations for ovarian cancer risk management.

Triple-Negative Breast Carcinoma

Triple-negative breast carcinomas (TNBCs) comprise approximately 15% to 20% of breast cancers. Accurate assessment of tumor estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) status is an essential part of classifying tumors into this group. As a group, these tumors are associated with poor clinical outcomes and have been shown to exhibit an increased propensity for hematogenous metastasis to the brain and lungs. Many TNBCs, particularly ductal, not otherwise specified (NOS), and metaplastic carcinomas, show an overlapping characteristic gene expression pattern when evaluated by cDNA microarrays. This group has been termed basal-like because of the similarity with normal breast basal/myoepithelial cells including basal cytokeratin expression and lack of hormone receptor and HER2 expression. The array data have been used to develop multiple immunohistochemical surrogates to identify basal-like tumors in formalin-fixed, paraffin-embedded tissues, most employing basal cytokeratins and epidermal growth factor receptor. Currently, there is no international consensus on biomarkers used to identify tumors as basal-like, and the routine use of the term basal-like in surgical pathology reports is premature. Tumor morphologic features associated with triple-negative status include Nottingham grade 3 with high mitotic rate, pushing border of invasion, geographic tumor necrosis, solid/sheet-like growth pattern, lymphocytic infiltrate, and large central acellular zone. Most breast cancers arising in patients who have a germ-line BRCA1 mutation show similar histologic features and a triple-negative phenotype. Not all TNBCs are associated with an unfavorable prognosis, drawing attention to the heterogeneity of this tumor group and the continued need to link tumor morphology and grade with triple-negative status. This article focuses on histopathology, molecular characterization, carcinogenesis, clinical behavior, and treatment of these tumors.

The prevalence of BRCA1 mutations among young women with triple-negative breast cancer

Background

Molecular screening for BRCA1 and BRCA2 mutations is now an established component of risk evaluation and management of familial breast cancer. Features of hereditary breast cancer include an early age-of-onset and over-representation of the 'triple-negative' phenotype (negative for estrogen-receptor, progesterone-receptor and HER2). The decision to offer genetic testing to a breast cancer patient is usually based on her family history, but in the absence of a family history of cancer, some women may qualify for testing based on the age-of-onset and/or the pathologic features of the breast cancer.

Methods

We studied 54 women who were diagnosed with high-grade, triple-negative invasive breast cancer at or before age 40. These women were selected for study because they had little or no family history of breast or ovarian cancer and they did not qualify for genetic testing using conventional family history criteria. BRCA1 screening was performed using a combination of fluorescent multiplexed-PCR analysis, BRCA1 exon-13 6 kb duplication screening, the protein truncation test (PTT) and fluorescent multiplexed denaturing gradient gel electrophoresis (DGGE). All coding exons of BRCA1 were screened. The two large exons of BRCA2 were also screened using PTT. All mutations were confirmed with direct sequencing.

Results

Five deleterious BRCA1 mutations and one deleterious BRCA2 mutation were identified in the 54 patients with early-onset, triple-negative breast cancer (11%).

Conclusion

Women with early-onset triple-negative breast cancer are candidates for genetic testing for BRCA1, even in the absence of a family history of breast or ovarian cancer.

Histopathological criteria and selection algorithms for BRCA1 genetic testing

To ensure targeted treatment, it would be useful to know at the time of diagnosis whether a BRCA mutation is causally related to an individual breast cancer. The aim of this study was to investigate in an unselected series of breast cancer patients the value of incorporating morphological and immunohistochemical features for the selection of patients who may benefit from BRCA1 genetic testing. In a retrospective approach, histopathological results of tumors from 897 women were reevaluated regarding age at diagnosis, subtype of cancer, tumor grade, and estrogen (ER), progesterone (PR), and Her2/neu receptor status, as well as p53 and Ki67 status. In all, 142 tumors fulfilled morphological criteria indicative of a BRCA1 mutation. Of the 59 women willing to participate, 26 women concomitantly showed a positive family history. Pathogenic BRCA1 germline mutations were detected in 7 of 18 women (39%) (95% confidence interval = 0.17-0.64). All BRCA1-associated tumors were of high grade, invasive-ductal subtype, and PR and Her2/neu negative, and 91% of the tumors were negative for ER; 60% of the tumors showed a high expression of p53 and 60% a high expression of Ki67. There was a significant difference with respect to grading (P = 0.001 for G3), ER negativity (P = 0.0075), Ki67 > or = 65% (P = 0.0039), and triple negativity (i.e., ER(-), PR(-), Her2/neu(-)) (P = 0.0019) between tumors of mutation carriers and noncarriers.

Hereditary breast cancer: from molecular pathology to tailored therapies

Hereditary breast cancer accounts for up to 5-10% of all breast carcinomas. Recent studies have demonstrated that mutations in two high-penetrance genes, namely BRCA1 and BRCA2, are responsible for about 16% of the familial risk of breast cancer. Even though subsequent studies have failed to find another high-penetrance breast cancer susceptibility gene, several genes that confer a moderate to low risk of breast cancer development have been identified; moreover, hereditary breast cancer can be part of multiple cancer syndromes. In this review we will focus on the hereditary breast carcinomas caused by mutations in BRCA1, BRCA2, Fanconi anaemia (FANC) genes, CHK2 and ATM tumour suppressor genes. We describe the hallmark histological features of these carcinomas compared with non-hereditary breast cancers and show how an accurate histopathological diagnosis may help improve the identification of patients to be screened for mutations. Finally, novel therapeutic approaches to treat patients with BRCA1 and BRCA2 germ line mutations, including cross-linking agents and PARP inhibitors, are discussed.

Hereditary breast cancer: part II. Management of hereditary breast cancer: implications of molecular genetics and pathology

Management of patients at high risk for hereditary breast cancer (HBC) must critically assess its phenotypic and genotypic heterogeneity, particularly evidenced by the varying spectra of cancer sites that are integral to the respective HBC syndromes. Targeted management must consider their biology, pathology, and molecular genetics, all in concert with their respective carcinogenic pathways, as they may differ significantly from one breast cancer syndrome to the next. A striking example of management differences pertains to BRCA1 and BRCA2 mutation-positive breast cancers wherein those with BRCA1 mutations are frequently estrogen receptor (ER)-negative in contrast to BRCA2 mutations which are more frequently ER-positive; therein, significant differences exist with respect to anti-estrogen therapy which will be more amenable to BRCA2 versus BRCA1 mutation carriers manifesting breast cancer. In turn, tumors that are negative for ER, PR, and Her2-neu, often referred to as "triple negative" tumors, may also harbor a unique basal-like gene expression profile and are characterized by poor prognosis wherein endocrine and/or Her2-neu-targeted therapies are not effective treatment options. A further confounder pertains to the lifetime risk for ovarian cancer, which differs strikingly between BRCA1 mutation carriers, who show a 40-60% lifetime risk, and their BRCA2 counterparts, who carry a lifetime risk of approximately 12-15% for ovarian cancer. It is clear that as we learn more about the biology and the molecular aspects of hereditary forms of breast cancer, it will be compelling for the clinician to integrate this knowledge with pharmacologic, radiologic, and surgical treatment options for these high-risk patients.

Triple negative breast carcinoma and the basal phenotype: from expression profiling to clinical practice

Triple negative breast carcinomas (TNBCs) are a group of primary breast tumors with aggressive clinical behavior. Most TNBCs possess a basal phenotype (BP) and show varying degrees of basal cytokeratin and myoepithelial marker expression. The importance of recognizing these tumors came to light largely as the result of gene expression profiling studies that categorized breast cancer into 3 major groups. Two of these groups are defined by their respective expression of estrogen receptor and HER2. TNBCs represent a third group and are defined by negativity for hormone receptors and HER2. TNBCs currently lack effective targeted therapies and are frequently resistant to standard chemotherapeutic regimens. These tumors tend to occur in premenopausal women and members of specific ethnic groups and a subset are associated with heritable BRCA1 mutations. For patients with sporadic TNBCs and BP tumors, BRCA1 dysfunction seems to play a major role in the development and progression of disease. The pathologist's role in the diagnosis and characterization of TNBCs and BP tumors is currently being defined as we are acquiring knowledge of the biologic and genetic underpinnings that drive this heterogeneous group of diseases. This review will provide a historical prospective on TNBCs and tumors that express basal cytokeratins and myoepithelial makers. Additionally, we will discuss the molecular biologic, genetic and pathologic aspects of these tumors. Guidelines will be provided on how to best approach the diagnosis of these cases and on what input pathologists should provide clinicians to help develop optimal therapeutic and preventative strategies against this aggressive group of breast cancers.

Demystifying basal-like breast carcinomas

"Basal" breast cancers are dominating the breast research literature at present and pathologists are under increasing pressure to evaluate for such a phenotype by their surgical and oncological colleagues. There is also much confusion about how to assess cancers, which immunohistochemical markers to use, what meaning and benefit this provides, and what the surgeons and oncologists will do with the information. Much remains to be done to answer all these questions but here we try to shed light on some of the issues and suggest what is still to come.