Abstract P3-08-06: Triple Negative Breast Cancer and BRCA Status: Implications for Genetic Counseling

Abstract

Abstract BACKGROUND: Controversy exists whether women newly diagnosed with triple negative breast cancer (TNBC) should be referred to genetic counseling as they may be more likely to be BRCA carriers. However, prior studies included small numbers of carriers and their results have had limited influence on practice guidelines. The objective of this study was to determine the association of breast cancer molecular subtype and BRCA status in a large group of medically insured women. METHODS: We examined a cohort of 2,105 women with breast cancer history tested for BRCA mutations in a large California health plan from 1997–2011. BRCA test results were recorded in the health plan's clinical genetics registry. Of the 2,105 breast cancer patients, 249 were BRCA mutation carriers (143 BRCA1 carriers, and 106 BRCA2 carriers). We conducted data linkages of all patients with the health plan's NCI-SEER affiliated tumor registry and identified ER, PR, and HER2. HER2 status was also captured from pathology reports using natural language processing. ER, PR, and HER2 status were assessed by immunohistochemical or FISH techniques. Patients were classified into four main biologic subtypes: triple negative (ER−/PR−/HER2−); luminal A (ER+ and/or PR+/HER2−); luminal B (ER+ and/or PR+/HER2+); and HER2-enriched (HER2+/ER−). We examined the association between molecular subtypes (collapsed into TNBC vs. non TNBC categories) and BRCA1/2 mutation status using contingency table analyses. P-values (two-sided) were estimated using chi-square analysis. Multivariable logistic regression was used to estimated adjusted odds ratios (OR) and 95% confidence intervals. RESULTS: TNBC subtype was strongly associated with BRCA status (P < 0.0001). Women with TNBC tumors were five-fold more likely to be BRCA carriers than women who had non-TNBC breast tumors (OR = 5.6, 95% CI: 4.1–7.5). Specifically, the association of TNBC with BRCA1 was more robust (OR = 12.2, 95% CI: 8.3–17.9). Adjusting for age and stage of breast cancer diagnosis and race/ethnicity did not materially modify the association between TNBC and BRCA1 status. TNBC was not associated with BRCA2 status (OR = 1.6, 95% CI: 0.9–2.7). CONCLUSION: TNBC was strongly associated with BRCA1 status, but not with BRCA2 status. Statistically significant numbers of patients with BRCA mutations have a TNBC profile. These patients should therefore be referred to clinical genetics for further evaluation and possible testing. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-08-06.