February 2013, Vol 2, No 1
Women With Triple-Negative Breast Cancer Highly Likely to Carry BRCA1 GeneUncategorized
Triple-negative breast cancer (TNBC) was strongly associated with BRCA1 status, but not with BRCA2 status, in a large study of medically insured women. The study showed that the number of patients with BRCA mutations with a TNBC profile is statistically significant.
The authors of this poster, presented at the 2012 Annual CTRC-AACR San Antonio Breast Cancer Symposium, suggest that patients with TNBC should be referred to a genetics counselor for further evaluation and possible genetic testing.
Women with TNBC are thought to be more likely to be BRCA carriers, but it is controversial whether newly diagnosed women with TNBC should be referred to genetic counseling. The recommendation for genetic counseling in this group of patients rests only on studies with small numbers of BRCA carriers. Thus, there is no clear guideline, explained lead author Reina Haque, PhD, MPH, Department of Research and Development, Kaiser Permanente Southern California, Pasadena, CA.
The study was conducted by investigators at Kaiser Permanente, a large nonprofit health plan serving over 3.5 million diverse members at more than 200 medical centers throughout southern California. The study was based on a retrospective cohort of 2105 women with breast cancer tested for BRCA mutations from 1997 to 2011. BRCA results were reported in the health plan’s clinical genetics registry. Of the 2105 breast cancer patients, 249 were BRCA mutation carriers: 143 BRCA1 carriers and 106 BRCA2 carriers.
Data linkages were performed for all patients with the Surveillance, Epidemiology, and End Results–affiliated tumor registry; estrogen receptor (ER), progesterone receptor (PR), and HER2 status was captured and assessed by immunohistochemical or fluorescence in situ hybridization techniques. Patients were classified into 2 main biologic subtypes: TNBC (ER negative, PR negative, HER2 negative); and non-TNBC (luminal A, luminal B, and HER2 enriched). The association between TNBC and non-TNBC and BRCA1 or BRCA2 mutation status was examined.
The investigators found that the TNBC subtype was strongly correlated with BRCA status (P<.0001). Women with TNBC tumors were 5 times more likely to be BRCA carriers than women with non-TNBC tumors (odds ratio [OR] 5.6; 95% CI, 4.1-7.5). The association between TNBC and BRCA1 was more robust (OR 12.2; 95% CI, 8.3-17.9). The association between TNBC and BRCA1 status was unchanged after adjusting for age, stage at diagnosis, and race/ethnicity. TNBC was not associated with BRCA2 status (OR 1.6; 95% CI, 0.9-2.7).
These findings in a large sample of women suggest that TNBC patients should be referred for further evaluation and genetic testing, as results may inform treatment choice.
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