BRCA testing and testing results among women 18–65 years old

Survival Outcomes in Women with Unilateral, Triple-Negative, Breast Cancer Correlated with Contralateral Prophylactic Mastectomy

BACKGROUND

Despite increased utilization of contralateral prophylactic mastectomy (CPM), there is insufficient evidence that it improves survival in average-risk women with unilateral breast cancer. CPM may be of heightened interest to patients with triple negative breast cancer (TNBC) because these patients are more likely to have BRCA1 mutation-associated disease and are not candidates for the chemoprevention benefits of adjuvant endocrine therapy.

METHODS

Survival and recurrence outcomes were evaluated for all TNBC patients from a multi-institutional database (1999-2018) at two academic cancer programs in two metropolitan cities of the Northeast and Midwest. Median follow-up time was 3.7 years.

RESULTS

Seven hundred and nighty six TNBC patients were evaluated and 15.45% underwent CPM. Women undergoing CPM were more likely to be white (p < 0.001), younger (p < 0.001), and underwent genetic testing (p < 0.001). A borderline survival benefit was observed for TNBC patients undergoing CPM (5-year overall survival 95.1% vs. 85.0%; p = 0.05). There was no difference in survival when BRCA mutation carriers were excluded (5-year overall survival 94.1% vs. 85.2%; p = 0.12). For BRCA mutation carriers, a numeric trend was observed for improved survival for patients undergoing CPM (5-year overall survival 97.2% vs. 84.1%; p = 0.35). Among patients not undergoing CPM, the rate of developing a new primary breast cancer was 2.2% (15/673). Among these 15 patients, 20% (3/15) were known BRCA mutation carriers.

CONCLUSIONS

Our data demonstrate no survival benefit for TNBC patients without BRCA1/2 mutations undergoing CPM.

Evaluation of a Four-Gene Panel for Hereditary Cancer Risk Assessment

BRCA1/2 are tumor suppressor genes involved in DNA double-strand break repair. They are the most penetrant genes for hereditary breast and ovarian cancers, but pathogenic variants in these two genes can be identified only in a fraction of hereditary cases. Following the diffusion of BRCA molecular testing and the availability of specific therapeutic strategies for the management of pathogenic variant carriers, the demand for the analysis of additional predisposing genetic factors has increased. Indeed, there is accumulating evidence regarding the role of other genes, including CHEK2 and PALB2. Both of them are involved in the same molecular pathway as BRCA genes, with CHEK2 being responsible for cell cycle stopping to allow the repair of DNA double-strand breaks and PALB2 being able to interact with BRCA1 and activate BRCA2. Thus, their role as additional hereditary cancer predisposing factors is intriguing. Accordingly, guidelines for hereditary cancer risk assessment have been updated to include the criteria for additional genes testing. In this context, we validated a commercially available kit allowing for the simultaneous analysis of BRCA1, BRCA2, CHEK2 and PALB2. Forty-eight patients, already tested for BRCA mutational status, were re-analyzed in the present study. Results comparison showed that the tested method was able to correctly identify all the variants previously detected in the same patients. In particular, all single-nucleotide variants and small indels were correctly identified. Moreover, two copy number variants, included to assess the software’s performance in detecting this kind of gene alteration, were also detected. Even if copy number variant estimation still requires confirmation by a molecular technique to avoid false positive results, it is able to reduce the number of patients requiring multiplex ligation probe amplification analysis, positively impacting the test’s turnaround time. Finally, since the time and costs of the analysis are similar to those required just for BRCA genes, this strategy may be affordable for providing a more comprehensive test for hereditary cancer risk assessment.