BRCA2 hereditary breast cancer pathophenotype

Evaluation of tumor-infiltrating lymphocytes and association with prognosis in BRCA-mutated breast cancer

BACKGROUND

Patients with a BRCA1 or BRCA2 mutation (BRCA-mutated breast cancer) are frequently diagnosed with low differentiated and highly proliferating breast cancer characterized by high amounts of tumor-infiltrating lymphocytes (Tils). Stromal Tils (sTils) are highly prognostic in sporadic triple-negative and HER2 positive breast cancer however, their prognostic importance in BRCA-mutated breast cancers is unknown.

MATERIAL AND METHODS

Formalin-fixed paraffin-embedded primary tumor tissue from 411 patients with a germline BRCA1 or BRCA2 mutation and diagnosed with early breast cancer was included. The percentage of sTils was quantified on full HE sections according to guidelines proposed by the Immuno-Oncology Biomarker in Breast Cancer Working Group. Distribution of sTils and associates with patient and tumor characteristics were assessed according to categorical sTils groups defined as low (<10%), intermediate (10-59%) and high (≥60%). Prognostic associations of sTils were evaluated as a continuous variable in univariate and multivariate models. Only follow-up time beyond date of BRCA mutation test was included.

RESULTS

A large proportion had high sTils (27% in the full cohort, 36% in BRCA1-mutated, and 44% in ER negative breast cancers). Higher sTils were associated with BRCA1, ER negative breast cancer, high histological grade and medullary histology. In combined analysis for BRCA1 and BRCA2-mutated breast cancers, increasing sTils in 10% intervals were significantly associated with OS (HR 0.92, 95% CI 0.84-1.00, p = .05). For each 10% increment of sTils in BRCA1 breast cancers, a 10% reduction of mortality (adjusted HR 0.90 95% CI 0.81-0.99, p = .03) and a 13% reduction in risk of DFS-event (HR 0.87 95% CI 0.76-1.00, p = .05) was observed even after adjustment for ER status. No significant association with survival was of observed in the BRCA2 subgroup. Test for interaction of sTils and BRCA status was not statistically significant (p = .3).

CONCLUSIONS

Breast cancer patients with a germline BRCA mutation had higher sTils than previously reported in sporadic breast cancers, and sTils were associated with favorable survival among BRCA carriers.

Predictors of survival for breast cancer patients with a BRCA1 mutation

PURPOSE

To evaluate in a contemporary cohort the impacts of chemotherapy and oophorectomy on survival for breast cancer patients with a BRCA1 mutation.

EXPERIMENTAL DESIGN

We reviewed the pathology reports and medical records of 372 women with breast cancer and a BRCA1 mutation, diagnosed from 2005 to 2017, between the ages of 25 and 65 and followed them for death from all causes and death from breast cancer. Death was ascertained through the Poland vital statistics registry. We performed survival analysis to evaluate the impacts of chemotherapy (including neoadjuvant cisplatinum) and of oophorectomy on survival.

RESULTS

After a mean follow-up of 5.6 years (median 5.2), 66 of the 372 women died; 56 of the deaths were from breast cancer and 6 were from ovarian cancer. 127 women received neoadjuvant cisplatinum and 245 women received other chemotherapies. Cisplatinum (versus all other therapies) was associated with a hazard ratio of 0.42 (95%CI 0.20-0.87) on breast cancer-specific survival. The 10-year actuarial all-cause survival for women who had both cisplatinum and an oophorectomy was 94.4%. The 10-year all-cause survival for women who had neither cisplatinum nor an oophorectomy was 65.4% (p < 0.01).

CONCLUSIONS

Cisplatinum and oophorectomy are effective therapies for women with breast cancer and a BRCA1 mutation.

Hereditary breast cancer: clinical, pathological and molecular characteristics

Pathogenic mutations in BRCA1 or BRCA2 are only detected in 25% of families with a strong history of breast cancer, though hereditary factors are expected to be involved in the remaining families with no recognized mutation. Molecular characterization is expected to provide new insight into the tumor biology to guide the search of new high-risk alleles and provide better classification of the growing number of BRCA1/2 variants of unknown significance (VUS). In this review, we provide an overview of hereditary breast cancer, its genetic background, and clinical implications, before focusing on the pathologically and molecular features associated with the disease. Recent transcriptome and genome profiling studies of tumor series from BRCA1/2 mutation carriers as well as familial non-BRCA1/2 will be discussed. Special attention is paid to its association with molecular breast cancer subtypes as well as the latest advances in predicting BRCA1/2 involvement (BRCAness) using molecular signatures, for improved diagnostics and selection of patients sensitive to targeted therapeutics.

Results of a phase II open-label, non-randomized trial of cisplatin chemotherapy in patients with BRCA1-positive metastatic breast cancer

INTRODUCTION

The purpose of this investigation was to evaluate the efficacy of cisplatin chemotherapy in BRCA1 mutation carriers with metastatic breast cancer.

METHODS

In a phase II, open-label study, 20 patients with metastatic breast cancer who carried a mutation in BRCA1 were treated with cisplatin 75 mg/m2 intravenously every 3 weeks as part of a 21-day cycle for 6 cycles. Restaging studies to assess response were performed after cycles 2 and 6, and every three months thereafter.

RESULTS

Between July 2007 and January 2009, 20 patients were enrolled. Baseline characteristics were as follows: 65% had prior adjuvant chemotherapy, 55% had prior chemotherapy for metastatic breast cancer; mean age was 48 years (ranges 32 to 70); 30% estrogen receptor (ER) or progesterone receptor (PR)+, 70% ER/PR/Human Epidermal Growth Factor Receptor 2 (HER2)- and 0% HER2+. Overall response rate was 80%; nine patients experienced a complete clinical response (45%) and seven experienced a partial response (35%). Overall survival was 80% at one year, 60% at two years and 25% at three years. Four of the 20 patients are alive four years after initiating treatment. The median time to progression was 12 months. The median survival from the start of cisplatinum treatment was 30 months. Cisplatin-related adverse events, including nausea (50%), anemia (5%) and neutropenia (35%) were mostly mild to moderate in severity.

CONCLUSIONS

This phase II study demonstrates that cisplatin chemotherapy has high activity in women with a BRCA1 mutation and metastatic breast cancer and is generally well tolerated.

TRIAL REGISTRATION

This trial is registered retrospectively on the clinical trials website ClinicalTrials.gov. The identifier is NCT01611727.

BRCA mutation testing in determining breast cancer therapy

BRCA mutation-associated breast cancer differs from sporadic breast cancer with regard to future cancer risks and sensitivity to systemic therapies. Now that rapid genetic testing for BRCA1 and BRCA2 mutations is available at the time of breast cancer diagnosis, BRCA mutation status can be considered when making treatment and prevention decisions for BRCA mutation carriers with breast cancer. This article reviews surgical options for management of affected BRCA mutation carriers with emphasis on the risks of ipsilateral recurrence and contralateral breast cancer. The roles of breast-conserving surgery, prophylactic mastectomy, and oophorectomy are reviewed. In addition, the sensitivity of BRCA mutation-associated breast cancer to endocrine therapy, platinum chemotherapy, and poly (ADP-ribose) polymerase inhibitors is reviewed.

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.

Is Mammographic Breast Density a Breast Cancer Risk Factor in Women With BRCA Mutations?

Purpose

Increased mammographic breast density is well recognized as a breast cancer risk factor in the general population. However, it is unclear whether it is a risk factor in women with BRCA mutations. We present the results of a nested case-control screening study investigating the relationship between breast density and breast cancer incidence in this population.

Patients and Methods

Women ages 25 to 65 years with known BRCA mutations were enrolled onto a single-center, high-risk breast cancer screening program. Using a computer-aided technique (Cumulus), quantitative percentage density (PD) was measured for each participant on her baseline mammogram by a single, blinded observer.

Results

Between November 1997 and March 2008, 462 women (mean age, 44 years; 245 BRCA1 and 217 BRCA2) were screened and 50 breast cancers were diagnosed (38 invasive, 12 ductal carcinoma in situ [DCIS]). Density was not measured in 40 women of whom four developed cancer (three invasive, one DCIS). Mean PD (± standard deviation [SD]) for 376 women who did not develop breast cancer was 34% (23) compared with 31% (21) for 46 women with cancer (P = .51). Logistic regression model of breast cancer incidence and PD revealed an odds ratio of 0.99 (± 0.01 SD) for a one-unit increase in PD (P = .44). Results remained nonsignificant in multivariate analysis, as well as when women with pure DCIS were excluded.

Conclusion

Increased mammographic breast density is not associated with higher breast cancer incidence in women with BRCA mutations. On the basis of these findings, density should not be considered a factor for these women in decision making regarding prophylactic surgery or chemoprevention.

High-Mobility Group A (HMGA) Proteins and Breast Cancer

The high-mobility group A (HMGA) protein family includes HMGA1a, HMGA1b and HMGA1c, which are encoded by the same gene through alternative splicing, and the closely related HMGA2 protein. HMGA proteins have been found to be abundant in several malignant neoplasias, including colorectal, prostate, cervical, lung, thyroid and breast carcinoma. HMGA proteins can be ideal candidates for the identification of new prognosis and diagnosis factors with non-invasive methods. To provide some clarity regarding the abundance of articles on this topic, here we focus on the relationship between HMGA proteins and breast cancer and their clinical perspective in the development of new therapeutic strategies.

Pathologic complete response rates in young women with BRCA1-positive breast cancers after neoadjuvant chemotherapy

PURPOSE

To estimate the rate of pathologic complete response (pCR) to neoadjuvant chemotherapy in BRCA1 mutation carriers according to chemotherapy regimen.

PATIENTS AND METHODS

From a registry of 6,903 patients, we identified 102 women who carried a BRCA1 founder mutation and who had been treated for breast cancer with neoadjuvant chemotherapy. Pathologic complete response was evaluated using standard criteria.

RESULTS

Twenty-four (24%) of the 102 BRCA1 mutation carriers experienced a pCR. The response rate varied widely with treatment: a pCR was observed in one (7%) of 14 women treated with cyclophosphamide, methotrexate, and fluorouracil (CMF); in two (8%) of 25 women treated with doxorubicin and docetaxel (AT); in 11 (22%) of 51 women treated with doxorubicin and cyclophosphamide (AC) or fluorouracil, doxorubicin, and cyclophosphamide (FAC), and in 10 (83%) of 12 women treated with cisplatin.

CONCLUSION

A low rate of pCR was observed in women with breast cancer and a BRCA1 mutation who were treated with AT or CMF. A high rate of pCR was seen after treatment with cisplatin. An intermediate rate of PCR was associated with AC or FAC. The relative benefits of AC and platinum therapy need to be confirmed through follow-up of this and other cohorts.

Subtypes of familial breast tumours revealed by expression and copy number profiling

Extensive expression profiling studies have shown that sporadic breast cancer is composed of five clinically relevant molecular subtypes. However, although BRCA1-related tumours are known to be predominantly basal-like, there are few published data on other classes of familial breast tumours. We analysed a cohort of 75 BRCA1, BRCA2 and non-BRCA1/2 breast tumours by gene expression profiling and found that 74% BRCA1 tumours were basal-like, 73% of BRCA2 tumours were luminal A or B, and 52% non-BRCA1/2 tumours were luminal A. Thirty-four tumours were also analysed by single nucleotide polymorphism-comparative genomic hybridization (SNP-CGH) arrays. Copy number data could predict whether a tumour was basal-like or luminal with high accuracy, but could not predict its mutation class. Basal-like BRCA1 and basal-like non-BRCA1 tumours were very similar, and contained the highest number of chromosome aberrations. We identified regions of frequent gain containing potential driver genes in the basal (8q and 12p) and luminal A tumours (1q and 17q). Regions of homozygous loss associated with decreased expression of potential tumour suppressor genes were also detected, including in basal tumours (5q and 9p), and basal and luminal tumours (10q). This study highlights the heterogeneity of familial tumours and the clinical consequences for treatment and prognosis.

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 and ovarian cancer syndrome : the impact of race on uptake of genetic counseling and testing

Breast cancer is a significant cause of morbidity and mortality in the United States. Although breast cancer is more common among White American (WA) women, incidence rates are higher among young African American (AA) women. Approximately 5-10% of all breast cancer can be accounted for by germline mutations in the breast cancer (BRCA)1 and BRCA2 genes responsible for hereditary breast and ovarian cancer (HBOC) syndrome. Although genetic counseling (GC) and genetic testing (GT) for HBOC have become widely accepted by the WA population, cancer genetic services are underused among AA. Many investigators have evaluated a wide spectrum of BRCA1 and BRCA2 mutations in the AA and African population with the possible identification of African founder mutations. Barriers to GC and GT include lack of knowledge and/or negative attitudes regarding genetics and genetics research, and concerns regarding the potential for racial discrimination. It is important for future research to focus on ways in which to eliminate barriers to GC and GT to alleviate disparity in the use of genetic services among high-risk AA women.

BRCA1/2 in high-risk African American women with breast cancer: providing genetic testing through various recruitment strategies

BACKGROUND

Due to the disproportionate numbers of African American women affected with early onset breast cancer, we sought to investigate mutation frequency of BRCA1 and BRCA2 (BRCA1/2) in a sample of African American women, recruited through a variety of methods.

METHODS

We conducted a study investigating BRCA1/2 among 51 African American breast cancer patients with a personal or family history suggestive of hereditary predisposition to breast cancer. All individuals underwent genetic counseling and BRCA1/2 mutation analysis, through protein-truncation test on exon 11 of BRCA1 and exons 10 and 11 of BRCA2, which together account for approximately 50% of mutations observed within these genes.

RESULTS

Of the 51 women tested for BRCA1/2 mutations, 3 were identified as mutation carriers (5.9%), including 1 in BRCA1 and 2 in BRCA2. Recruitment strategies varied and included physician referrals from the Moffitt Cancer Center Breast Program (18), community-based oncologists (13), primary care physicians (3), newspaper advertisements and brochures (5), community or support group referrals (7), self/family referral through word of mouth (2), and the Florida State Cancer Registry (3).

CONCLUSIONS

Our results suggest that (1) BRCA1/2 mutations are seen in high-risk African American women with breast cancer, and (2) strategies for recruitment of African American women in studies of genetic testing for breast cancer genes have varied levels of success. Our study highlights the need for further studies in this population group.

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.

Response to neo-adjuvant chemotherapy in women with BRCA1-positive breast cancers

PURPOSE

There have been no studies to date which look at the relative effectiveness of different regimens of chemotherapy in women who have breast cancer and who carry a BRCA1 germ-line mutation. We wished to compare rates of response to neo-adjuvant chemotherapy in BRCA1 mutation carriers and non-carrier controls.

EXPERIMENTAL DESIGN

From a registry of 3,479 patients, we identified 44 Polish women who carried a BRCA1 founder mutation and who had been treated with neo-adjuvant chemotherapy for breast cancer, and 41 age- and hospital-matched controls.

RESULTS

35 of the 44 BRCA1 mutation carriers (80%) experienced a partial or complete response to neo-adjuvant chemotherapy, compared to 39 of the 41 (95%) non-carriers (P=0.05). In the hereditary subgroup, response rates differed depending on whether or not a taxane (docetaxel) was given. Six of the 15 BRCA1 carrier women given docetaxel with doxorubicin responded (complete or partial), compared to 29 of 29 given other (DNA-damaging) therapies (P=0.001). Among the non-carriers, the rates of response to the two categories of chemotherapy were similar.

CONCLUSIONS

Breast cancers among BRCA1 carriers frequently do not exhibit sensitivity to docetaxel in the neo-adjuvant setting. It is likely that normal BRCA1 is required for clinical response to mitotic spindle poisons.

BRCA2 mutation-associated breast cancers exhibit a distinguishing phenotype based on morphology and molecular profiles from tissue microarrays

A distinct morphologic and molecular phenotype has been reported for BRCA1-associated breast cancers; however, the phenotype of BRCA2-associated breast cancers is less certain. To comprehensively characterize BRCA2-associated breast cancers we performed a retrospective case control study using tumors accrued through the Breast Cancer Family Registry. We examined the tumor morphology and hormone receptor status in 157 hereditary breast cancers with germline mutations in BRCA2 and 314 control tumors negative for BRCA1 and BRCA2 mutations that were matched for age and ethnicity. Tissue microarrays were constructed from 64 BRCA2-associated and 185 control tumors. Tissue microarray sections were examined for HER2/neu protein overexpression, p53 status and the expression of basal markers, luminal markers, cyclin D1, bcl2, and MIB1 by immunohistochemistry. The majority of BRCA2-associated tumors and control tumors were invasive ductal, no special-type tumors. In contrast to control tumors, BRCA2-associated cancers were more likely to be high grade (P<0.0001) and to have pushing tumor margins (P=0.0005). Adjusting for grade, BRCA2-associated tumors were more often estrogen receptor positive (P=0.008) and exhibited a luminal phenotype (P=0.003). They were less likely than controls to express the basal cytokeratin CK5 (P=0.03) or to overexpress HER2/neu protein (P=0.06). There was no difference in p53, bcl2, MIB1, or cyclin D1 expression between BRCA2-associated and control tumors. We have demonstrated, in the largest series of BRCA2-associated breast cancers studied to date, that these tumors are predominantly high-grade invasive ductal carcinomas of no special type and they demonstrate a luminal phenotype despite their high histologic grade.

Pathology and gene expression of hereditary breast tumors associated with BRCA1, BRCA2 and CHEK2 gene mutations

Tumors arising in BRCA1 and BRCA2 mutation carriers appear to have specific pathological and gene expression profiles, which show a high level of concordance. BRCA1 tumors are high-grade, negative for hormone receptors, have a high proliferation rate, and are positive for some cell cycle promoter genes. BRCA2 tumors present a phenotype opposite to BRCA1 tumors but very similar to sporadic tumors, except that BRCA2 overexpress some DNA repair markers such as CHEK2, show high cytoplasmic expression of RAD51, and are negative for HER-2 amplification and expression. Some of these characteristics have also been found in cDNA expression studies, although more analysis are necessary in order to obtain new markers that can be associated with a germ line mutation in BRCA1 or BRCA2. In this way, some studies in normal tissues of BRCA1/2 carriers suggest that differences exist in the level of expression of some genes when compared with noncarriers. Finally, IHC studies in tumors carrying a mutation in CHEK2 are rare and show contradictory results, probably due to the low number of these cases. However, they represent an example showing how different mutations of the same gene may be associated with specific histological subtypes of cancer.

Patterns of cancer incidence, mortality, and prevalence across five continents: defining priorities to reduce cancer disparities in different geographic regions of the world

Efforts to reduce global cancer disparities begin with an understanding of geographic patterns in cancer incidence, mortality, and prevalence. Using the GLOBOCAN (2002) and Cancer Incidence in Five Continents databases, we describe overall cancer incidence, mortality, and prevalence, age-adjusted temporal trends, and age-specific incidence patterns in selected geographic regions of the world. For the eight most common malignancies-cancers of lung, breast, colon and rectum, stomach, prostate, liver, cervix, and esophagus-the most important risk factors, cancer prevention and control measures are briefly reviewed. In 2002, an estimated 11 million new cancer cases and 7 million cancer deaths were reported worldwide; nearly 25 million persons were living with cancer. Among the eight most common cancers, global disparities in cancer incidence, mortality, and prevalence are evident, likely due to complex interactions of nonmodifiable (ie, genetic susceptibility and aging) and modifiable risk factors (ie, tobacco, infectious agents, diet, and physical activity). Indeed, when risk factors among populations are intertwined with differences in individual behaviors, cultural beliefs and practices, socioeconomic conditions, and health care systems, global cancer disparities are inevitable. For the eight most common cancers, priorities for reducing cancer disparities are discussed.

BRCA1-positive breast cancers in young women from Poland

We identified 4316 unselected incident cases of early-onset breast cancers (<51 ears of age at diagnosis) in 18 Polish hospitals between 1996 and 2003. We were able to obtain a blood sample for DNA analysis from 3472 of these (80.4%). All cases were tested for the presence of three founder mutations in BRCA1. The proportion of cases with a BRCA1 mutation was 5.7%. The hereditary proportions were higher than this for women with breast cancer diagnosed before age 40 (9%), for women with cancer of medullary or atypical medullary histology (28%), for those with bilateral cancer (29%) or with a family history of breast or ovarian cancer (13%). It is reasonable to offer genetic testing to women with early-onset breast cancer in Poland.

Histopathology of BRCA1- and BRCA2-associated breast cancer

Hereditary breast carcinomas that are attributable to BRCA1/2 mutations have their own morphological and immunohistochemical characteristics. BRCA1-associated carcinomas are poorly differentiated infiltrating ductal carcinomas that frequently show morphological features of typical or atypical medullary carcinoma. BRCA2-associated breast carcinomas tend to be of higher grade than sporadic age-matched controls. BRCA1tumors have been found to be more frequently estrogen receptor- and progesterone receptor-negative, and p53-positive than are age-matched controls, whereas these differences are not usually found in BRCA2-associated tumors. In addition, BRCA1- and BRCA2-associated breast carcinomas show a low frequency of HER2 expression. Most BRCA1 breast carcinomas are characterized by the expression of basal (myoepithelial) markers, such as cytokeratin 5/6 and or P-cadherin. These features could be used to distinguish patients who are likely to carry a BRCA1 or BRCA2 germline mutation, thus indicating which gene should be screened for first in families with a high incidence of breast and ovarian cancer.

A common missense variant in BRCA2 predisposes to early onset breast cancer

Introduction

Mutations in the BRCA2 gene are one of the two major causes of hereditary breast cancer. Protein-truncating mutations of BRCA2 are usually deleterious and increase the risk of breast cancer up to 80% over a lifetime. A few missense mutations in BRCA2 are believed to have a similarly high penetrance, apart from more common neutral polymorphisms. It is often difficult to classify a particular sequence variant as a mutation or a polymorphism. For a deleterious variant, one would expect a greater allele frequency in breast cancer cases than in ethnic-matched controls. In contrast, neutral polymorphic variants should be equally frequent in the two groups.

Methods

We genotyped 3,241 cases of breast cancer diagnosed at under 51 years of age, unselected for family history, from 18 hospitals throughout Poland and 2,791 ethnic-matched controls for a single BRCA2 C5972T variant.

Results

The variant was present in approximately 6% of the Polish population. In the study, 13 women (11 cases and two controls (OR = 4.7; p = 0.02)) were homozygous for the variant allele. The overall odds ratio for breast cancer in women with a single copy of the BRCA2 C5972T variant was 1.1 (p = 0.7); however, the effect was significant for patients diagnosed at or before age 40 (OR = 1.4; p = 0.04). We reviewed the association between the BRCA2 variant in different histologic subgroups and found the effect most pronounced in women who had ductal carcinoma in situ (DCIS) with micro-invasion (OR = 2.8; p < 0.0001).

Conclusion

The BRCA2 C5972T allele is a common variant in Poland that increases the risk of DCIS with micro-invasion. The homozygous state is rare but increases the risk of breast cancer five-fold.

The molecular pathology of hereditary breast cancer: genetic testing and therapeutic implications

Cancer arising in carriers of mutations in the BRCA1 and BRCA2 genes differs from sporadic breast cancer of age-matched controls and from non-BRCA1/2 familial breast carcinomas in its morphological, immunophenotypic and molecular characteristics. Most BRCA1 carcinomas have the basal cell phenotype, a subtype of high-grade, highly proliferating, estrogen receptor- and HER2-negative breast carcinomas, characterized by the expression of basal or myoepithelial markers such as basal keratins, P-cadherin, epidermal growth factor receptor, etc. This phenotype is rarely found in BRCA2 carcinomas, which are of higher grade than sporadic age-matched controls, but tend to be estrogen receptor- and progesterone receptor-positive. The expression of the cell-cycle proteins cyclins A, B1 and E and SKP2 is associated with a BRCA1 phenotype, whereas cyclin D1 and p27 expression is associated with BRCA2 carcinomas. Recent studies have shown that hereditary carcinomas that are not attributable to BRCA1/2 mutations have phenotypic similarities to BRCA2 tumors, but tend to be of lower grade and proliferation index. Somatic mutations in the BRCA genes are rarely found in hereditary tumors; by contrast, BRCA1 and BRCA2 loss of heterozygosity (LOH) is found in almost all BRCA1 and BRCA2 carcinomas, respectively. Furthermore, all types of hereditary breast carcinomas have a low frequency of HER2 expression. Finally, comparative genomic hybridization studies have revealed differences in chromosomal gains and losses between genotypes. The pathological and molecular features of hereditary breast cancer can drive specific treatments and influence the process of mutation screening. In addition, detecting molecular changes such as BRCA1/2 LOH in nonatypical cells obtained by random fine-needle aspiration, ductal lavage or nipple aspirate fluid may help to earlier identify carrier women who are at an even higher risk of developing breast carcinoma.

The pathology of hereditary breast cancer

Several studies have demonstrated that familial breast cancers associated with BRCA1 or BRCA2 germline mutations differ in their morphological and immunohistochemical characteristics. Cancers associated with BRCA1 are poorly differentiated infiltrating ductal carcinomas (IDCs) with higher mitotic counts and pleomorphism and less tubule formation than sporadic tumours. In addition, more cases with the morphological features of typical or atypical medullary carcinoma are seen in these patients. Breast carcinomas from BRCA2 mutation carriers tend to be of higher grade than sporadic age-matched controls. Regarding immunophenotypic features. BRCA1 tumours have been found to be more frequently oestrogen receptor- (ER) and progesterone receptor-(PR) negative, and p53-positive than age-matched controls, whereas these differences are not usually found in BRCA2-associated tumours. A higher frequency and unusual location of p53 mutations have been described in BRCA1/2 carcinomas. Furthermore, BRCA1- and BRCA2-associated breast carcinomas show a low frequency of HER-2 expression. Recent studies have shown that most BRCA1 carcinomas belong to the basal cell phenotype, a subtype of high grade, highly proliferating ER/HER2-negative breast carcinoma characterized by the expression of basal or myoepithelial markers, such as basal keratins, P-cadherin, EGFR, etc. This phenotype occurs with a higher incidence in BRCA1 tumours than in sporadic carcinomas and is rarely found in BRCA2 carcinomas. Hereditary carcinomas not attributable to BRCA1/2 mutations have phenotypic similarities with BRCA2 tumours, but tend to be of lesser grade and lower proliferation index. The pathological features of hereditary breast cancer can drive specific treatment and influence the process of mutation screening.

p53 inactivation is a rare event in familial breast tumors negative for BRCA1 and BRCA2 mutations

Germline mutations at BRCA1 or BRCA2 genes result in susceptibility to breast and ovarian cancers. BRCA1- and BRCA2-associated tumors have distinct histologic and molecular phenotypes, as compared to sporadic breast tumors. Typically, a higher grade of malignancy is observed in BRCA-associated cancers. A number of studies have suggested that BRCA1 and BRCA2 proteins are of importance in DNA repair and maintenance of genome integrity, bringing about molecular models of tumor pathogenesis. In particular, alterations at p53 gene have been suggested to be a necessary step in the tumorigenesis of BRCA-associated carcinomas. In fact, BRCA-associated breast cancers have higher p53 mutation frequencies than sporadic ones. At present, very little is known regarding BRCA non-associated familial tumors (termed BRCAx tumors). To our knowledge no data is available on p53 alterations in this sub-group of familial tumors. In this study p53 alteration frequencies were evaluated in 13 BRCA1, 11 BRCA2 and 55 BRCAx breast tumors. Tumor samples were analyzed for p53 gene mutations by PCR-SSCP/direct sequencing, and for p53 protein overexpression by immunohistochemistry (IHC). Altogether, p53 alterations were detected in 54% of BRCAI tumors compared with 5% of BRCAx tumors. No p53 alteration was found in BRCA2 tumors. While loss of p53 checkpoint control is likely to be an important step in the molecular pathogenesis of BRCA1-associated cancers, our data seem to indicate a p53-independent molecular mechanism underlying BRCAx neoplastic transformation.

Familial breast cancer: an investigation into the outcome of treatment for early stage disease

The purpose of this study was to retrospectively compare the outcomes of treatment in 304 women with familial and sporadic breast cancer to clarify the options for the primary management of familial breast cancer. The majority of women were consecutively ascertained on the basis of either breast cancer diagnosed at age < 40 years or bilateral breast cancer. In addition, known BRCA1 mutation carriers were identified through the genetics services in participating centres. These patients were subdivided into those with a significant family history of breast cancer or known BRCA1 mutation (FH+) and those with no significant family history (FH-). There were no significant differences in age, surgical treatment or adjuvant treatment between the two groups, but there were significantly more women whose nodal status was unknown in the FH+ group. Ipsilateral recurrence occurred in 22.2% of FH+ patients compared with 24.1% of FH- patients (p = 0.774) who underwent breast conserving surgery. There was a striking excess of contralateral breast cancers in the FH+ group (35.9% v 16%, p = 0.0007), with a cumulative risk of contralateral cancer of 36% at 10 years. This was reflected in a non-significant trend toward worse relapse free survival in the FH+ group (p = 0.0563), but no difference was observed in overall survival between the two patient groups (p = 0.142). Similarly, for patients with known BRCA1 mutations, contralateral recurrence occurred more frequently, but other outcomes were not significantly different from the FH- group. Breast conserving treatment is not associated with an increased risk of local recurrence in women with familial breast cancer and the prognosis of these women appears to be similar to that of young women with apparently sporadic breast cancer. However, the risk of contralateral breast cancer is significant in the FH+ group and should be considered in planning primary treatment and follow up.

Hereditary breast-ovarian cancer at the bedside: role of the medical oncologist

PURPOSE

To provide practical considerations for diagnosing, counseling, and managing patients at high risk for hereditary breast cancer.

DESIGN

We have studied 98 extended hereditary breast cancer (HBC)/hereditary breast-ovarian cancer (HBOC) families with BRCA1/2 germline mutations. From these families, 1,315 individuals were counseled and sampled for DNA testing. Herein, 716 of these individuals received their DNA test results in concert with genetic counseling. Several challenging pedigrees were selected from Creighton University's hereditary cancer family registry, as well as one family from Evanston/Northwestern Healthcare, to be discussed in this present report.

RESULTS

Many obstacles were identified in diagnosis, counseling, and managing patients at high risk for HBC/HBOC. These obstacles were early noncancer death of key relatives, perception of insurance or employment discrimination, fear, anxiety, apprehension, reduced gene penetrance, and poor compliance. Other important issues such as physician culpability and malpractice implications for failure to collect or act on the cancer family history were identified.

CONCLUSION

When clinical gene testing emerged for BRCA1 and BRCA2, little was known about the efficacy of medical interventions. Potential barriers to uptake of testing were largely unexplored. Identification and referral of high-risk patients and families to genetic counseling can greatly enhance the care of the population at the highest risk for cancer. However, because premonitory physical stigmata are absent in most of these syndromes, an HBOC diagnosis may be missed unless a careful family history of cancer of the breast, ovary, or several integrally associated cancers is obtained.

Breast cancer genetics in African Americans

BACKGROUND

An overview of the state of genetic testing for BRCA1 and BRCA2 genes was presented at the Summit Meeting on Breast Cancer Among African American women.

METHODS

An exhaustive literature search was performed using PubMed and abstracts published from meetings of the American Association for Cancer Research, the American Society of Human Genetics, and the American Society of Clinical Oncology. The Breast Cancer Information Core was also searched for information regarding sequence variants in which the ethnicity of the individual tested was known.

RESULTS

Of the 26 distinct BRCA1 pathogenic mutations (protein-truncating, disease-associated missense, and splice variants) detected in Africans or African Americans, 15 (58%) have not been previously reported. In addition, 18 deleterious BRCA2 mutations have been identified and 10 (56%) of these are unique to the group. Only two pathogenic BRCA1 mutations (943ins10 and M1775R) have been detected in three or more unrelated families. However, seven additional BRCA1 or BRCA2 deleterious mutations have been reported in at least two unrelated families. Three of these recurrent BRCA1 mutations (943ins10, 1832del5, and 5296del4) have been characterized by haplotype studies and each likely arose from a common ancestor, including one ancestor that could be traced to the Ivory Coast in West Africa. Although only a few African-American families have been tested for BRCA1 and BRCA2 mutations, the probability of finding a mutation is invariably dependent on the age of onset and the number of breast and/or ovarian cancer cases in the family. The psychosocial implications of genetic testing for African Americans have not been well studied, so that high-risk African Americans may underestimate their risks of breast and ovarian cancer.

CONCLUSIONS

Deleterious BRCA1 and BRCA2 mutations have been identified in African-American and African families. A number of unique mutations have been described, but recurrent mutations are widely dispersed and are not readily identifiable in the few families that have been tested. Access to genetic counseling and testing in a culturally sensitive research setting must remain a high priority before genetic testing can be disseminated in the community.

The pathology of inherited breast cancer

Familial breast cancer has been recognised for many years. In the 1990s the genetic mechanism of inheritance of a proportion of these familial cancers was found to be attributable to germline mutation in either of two newly discovered genes, namely BRCA1 and BRCA2. Since the discovery of these genes, studies have been performed in which the pathological characteristics of familial cancers arising in patients with germline BRCA1 and BRCA2 mutation have been examined. A distinct pathological phenotype of high-grade, oestrogen receptor-negative breast cancer, often with medullary features, has been consistently described for BRCA1 cancers. A less distinct phenotype has been described for BRCA2 cancers. The discovery of genotype-phenotype correlation has significant implications for patient management and novel treatment strategies, not only for inherited cancers, but for breast cancer in general.

The pathology of familial breast cancer: predictive value of immunohistochemical markers estrogen receptor, progesterone receptor, HER-2, and p53 in patients with mutations in BRCA1 and BRCA2

PURPOSE

The morphologic and molecular phenotype of breast cancers may help identify patients who are likely to carry germline mutations in BRCA1 and BRCA2. This study evaluates the immunohistochemical profiles of tumors arising in patients with mutations in these genes.

MATERIALS AND METHODS

Samples of breast cancers obtained from the International Breast Cancer Linkage Consortium were characterized morphologically and immunohistochemically using antibodies to estrogen receptor, progesterone receptor, HER-2 (c-erbB-2 oncogene), and p53 protein.

RESULTS

Breast cancers in patients with BRCA1 germline mutations are more often negative for estrogen receptor, progesterone receptor, and HER-2, and are more likely to be positive for p53 protein compared with controls. In contrast, BRCA2 tumors do not show a significant difference in the expression of any of these proteins compared with controls.

CONCLUSION

BRCA1 has a distinctive morphology and immunohistochemical phenotype. The combined morphologic and immunohistochemical data can be used to predict the risk of a young patient harboring a germline mutation in BRCA1. The BRCA2 phenotype is currently not well defined.

[Clinical and pathological characteristics and clinical course of patients with breast cancer and BRCA1/BRCA2 mutations]

BACKGROUND

Clinico-pathological differences between BRCA1 or BRCA2 mutation-associated breast cancer (BC) and sporadic BC are little known.

PATIENT AND METHODS

We analysed the clinico-pathological characteristics and clinical follow-up of 30 patients with BC. BRCA1 and BRCA2 mutations were detected by SSCP and PTT.

RESULTS

There were no differences in age, size or nodal status at the time of diagnosis. Mammography features were more heterogeneous in BRCA2 than in BRCA1 BC. All BRCA1 mutation-associated BC corresponded to infiltrating ductal carcinomas (20% medullary carcinomas) with a more aggressive pathological behavior. The frequency of local recurrences was 14% in BRCA1 and 20% in BRCA2. Contralateral BC and ovarian cancer (OC) were observed in 27% and 20% of BRCA1 cases, respectively, and 6% and 6% of BRCA2 cases. The median follow-up in BRCA1 and BRCA2 BC was 131 and 54 months, respectively.

CONCLUSIONS

There were no differences in age at diagnosis and stage between BRCA1 and BRCA2 breast cancer. The mammographic pattern in BRCA2 was more heterogeneous. BRCA1 mutations were associated with more aggressive histopathologic findings and a higher risk of a second BC and OC.

Quantitative analysis of BRCA1 and BRCA2 mRNA expression in sporadic breast carcinomas and its relationship with clinicopathological characteristics

BRCA1 and BRCA2 mRNA expression in sporadic breast cancers was quantified by a real-time reverse transcriptase-polymerase chain reaction (RT-PCR), and the relationship of their expression with various clinicopathological factors was studied. BRCA2 mRNA levels (0.993 +/- 1.395, mean +/- SD (BRCA2 / beta-glucuronidase mRNA ratios)) were significantly (P < 0.01) higher than BRCA1 mRNA levels (0.519 +/- 0.570 (BRCA1 / beta-glucuronidase mRNA ratios)), and a weak but significant (r = 0.390, P < 0.01) correlation was observed between BRCA1 and BRCA2 mRNA expression levels. There was no significant association between BRCA1 mRNA expression and clinicopathological factors such as menstrual status, tumor size, lymph node status, estrogen and progesterone receptor status, and histological grade. On the other hand, there was a significant association between higher BRCA2 mRNA expression and estrogen receptor (ER) negativity (P < 0.01) or progesterone receptor (PR) negativity (P < 0.01) or high histological grade (P < 0.01). These results suggest a differential contribution of BRCA1 and BRCA2 in the pathogenesis of sporadic breast cancers. BRCA2 mRNA is speculated to be up-regulated in response to proliferation and genomic instability in high histological grade tumors.

Gene-expression profiles in hereditary breast cancer

BACKGROUND

Many cases of hereditary breast cancer are due to mutations in either the BRCA1 or the BRCA2 gene. The histopathological changes in these cancers are often characteristic of the mutant gene. We hypothesized that the genes expressed by these two types of tumors are also distinctive, perhaps allowing us to identify cases of hereditary breast cancer on the basis of gene-expression profiles.

METHODS

RNA from samples of primary tumor from seven carriers of the BRCA1 mutation, seven carriers of the BRCA2 mutation, and seven patients with sporadic cases of breast cancer was compared with a microarray of 6512 complementary DNA clones of 5361 genes. Statistical analyses were used to identify a set of genes that could distinguish the BRCA1 genotype from the BRCA2 genotype.

RESULTS

Permutation analysis of multivariate classification functions established that the gene-expression profiles of tumors with BRCA1 mutations, tumors with BRCA2 mutations, and sporadic tumors differed significantly from each other. An analysis of variance between the levels of gene expression and the genotype of the samples identified 176 genes that were differentially expressed in tumors with BRCA1 mutations and tumors with BRCA2 mutations. Given the known properties of some of the genes in this panel, our findings indicate that there are functional differences between breast tumors with BRCA1 mutations and those with BRCA2 mutations.

CONCLUSIONS

Significantly different groups of genes are expressed by breast cancers with BRCA1 mutations and breast cancers with BRCA2 mutations. Our results suggest that a heritable mutation influences the gene-expression profile of the cancer.

Germ line mutations associated with breast cancer susceptibility

Laboratory-based research in germ line mutations associated with breast cancer susceptibility is rapidly being integrated into clinical practice with profound implications. A Medline search was performed for all relevant articles published since 1990. Where appropriate, historical articles referenced in those identified were also reviewed. The results suggested that while mutations in the BRCA1 and BRCA2 genes are the most clinically relevant, much of the data on which clinical decisions are based must be interpreted with wide confidence intervals. Between 1 in 152 and 1 in 833 individuals carry such mutations. They account for less than 5% of all breast cancer, but up to 10% of cancers in those under the age of 40 years. Founder mutations are responsible for a larger proportion of breast cancer cases within certain inbred communities. Phenotypic expression and penetrance of different mutations is not currently predictable and estimates of penetrance are largely based on highly selected populations. BRCA1 mutations are more commonly associated with ovarian cancer than BRCA2 mutations. BRCA1 cancers tend to have more distinct pathological features and are usually oestrogen receptor (ER)-negative. To conclude, the evidence in this review suggests that caution should be exercised when translating scientific progress in breast cancer germ line genetics into clinical practice. Most of the available data are derived from studies on highly selected populations. The importance of other less penetrant, but more prevalent, germ line mutations may be realised in the future.

Historical and epidemiologic background of human premalignant breast disease

Premalignant breast disease in humans is a concept that admits to a broad range of elements and possible determinants predicting the likelihood of developing breast cancer. Most of these elements are relative, such as the risk of breast cancer for women that is 130 times that of men and peaks at a younger age by about 10 years. Breast cancer is clearly a stochastic, multifactorial process that evolves over many years in which we must make predictions by likelihood. This review will present the most specially defined and reliably proven of these elements, highlighting anatomic and molecular factors.

Clinico-pathological characteristics of BRCA1- and BRCA2-related breast cancer

Approximately 2% to 5% of all breast cancers are hereditary, meaning that the cancer predisposition is carried as a monogenic trait. Several highly penetrant breast cancer predisposing genes have been identified. These discoveries will permit a refined description of breast cancer occurring as part of the different genetic syndromes. We reviewed the medical literature on the clinico-pathological features of breast cancer associated with the major breast cancer susceptibility genes BRCA1 and BRCA2. BRCA1-associated breast cancers are more frequently ductal invasive, high-grade carcinomas with an important lymphocytic infiltration. They are aneuploid, estrogen and progesterone receptors negative, and p53 positive. BRCA2-related breast cancers tend to be higher-grade tumors than are non-hereditary cases, although this association is less strong then for BRCA1 cases. These tumors exhibit substantially less tubule formation, but mitotic count and cellular pleomorphism do not differ significantly from those of sporadic cases. The overall pattern of the identified pathological characteristics suggests a carcinogenic pathway in BRCA1- and BRCA2-related breast cancers different from that found in sporadic cases. The probability of finding a BRCA1/2 germ-line mutation is partly determined by these characteristics. In addition, these features will likely influence the behavior of BRCA1/2-related breast cancer.

Breast carcinomas arising in carriers of mutations in BRCA1 or BRCA2: are they prognostically different?

PURPOSE

To review the preclinical and clinical studies relevant to the prognosis and prognostic associations of BRCA1- and BRCA2-associated breast carcinomas, with an emphasis on research methodology.

METHODS

Reports of relevant studies obtained from a MEDLINE search, and references from these articles, were critically reviewed.

RESULTS

Consistent associations with both favorable (medullary or atypical medullary carcinoma) and unfavorable (high tumor grade, hormone receptor negativity, somatic p53 mutation) prognostic characteristics have been found for BRCA1-associated breast carcinomas. Inconsistent results have been demonstrated for prognostic associations of BRCA2-associated breast tumors. Clinical studies that have directly assessed the prognosis of these tumors have not shown a clear effect of BRCA1 or BRCA2 mutation, but no study has used optimal methodology. In vitro and animal model data suggest a possible influence of these mutations on response to agents that cause double-strand DNA breaks, but clinical data are limited.

CONCLUSION

The elucidation of an identifiable subgroup of breast carcinomas that result from germline mutations in BRCA1 or BRCA2 may be an important step toward genotype-based understanding of prognosis and choice of therapy in this disease. However, currently there are inadequate data to support use of BRCA1 or BRCA2 status to counsel individuals regarding their prognosis or to select treatment. Well-designed studies of population-based inception cohorts of breast cancer patients, which have adequate sample size and complete follow-up, and which use objective outcome criteria and blinding of outcome assessment, are required to optimally address this question.

Breast cancer susceptibility genes. BRCA1 and BRCA2

Mutations in the BRCA1 and BRCA2 genes lead to an increased susceptibility to breast, ovarian, and other cancers. It is estimated that 3%-8% of all women with breast cancer will be found to carry a mutation in 1 of these genes. Families with multiple affected first-degree relatives and patients with early-onset disease have been found to harbor mutations at a higher frequency. The BRCA1 and BRCA2 genes code for large proteins that bear no resemblance to other known genes. In the cell, they appear to act as tumor suppressor genes and play a role in the maintenance of genome integrity, although the precise function of these genes has yet to be discovered. A large number of distinct mutations have been found in cancer families around the world. The majority of the defined pathologic mutations result in premature truncation of the protein (frameshift and nonsense mutations). These mutations may substantially increase the risk for breast and ovarian cancer, but a precise risk estimate for each different mutation cannot be determined. Depending on the familial context, the risk of breast cancer associated with carrying a mutation has been estimated to range from 50% to 85%. The role of these genes in sporadic cancer remains unknown. Patients and physicians considering BRCA1 and BRCA2 genetic testing are faced with a difficult decision. The diversity of mutations and lack of general population data prevent accurate risk prediction. This is further complicated by the paucity of data on effective prevention strategies for those identified at higher risk. Thus, the nature of clinical testing for BRCA1 and BRCA2 continues to present challenges that reinforce the necessity of personal choice within the context of thorough genetic counseling.