Baseline E2 levels are higher in BRCA2 mutation carriers: a potential target for prevention?

BRCA gene mutations and elevated serum estradiol (E-2) are well-known risk factors for breast cancer. The aim of this study was to investigate the association between BRCA gene mutations and serum E-2 level. We measured baseline (menstrual cycle day 2-3) E-2 levels of 96 women with breast cancer who underwent BRCA testing. The mean age, parity, and age at menarche did not differ between women with and without BRCA1/2 mutations. Basal serum E-2 level was significantly higher in women with BRCA2 mutations compared to women with BRCA1 mutations or without BRCA mutations (71.7 +/- A 41.6 vs. 45.5 +/- A 20.7 vs. 38.5 +/- A 12.6 pg/ml in BRCA2 mutation carriers, BRCA1 mutation carriers, and non-carriers, respectively, p value = 0.03). Women with BRCA2 mutations had 3.1 times as great risk for high basal E-2 level (> 48 pg/ml) as women without BRCA mutations after adjusting for age and BMI (95 % confidence interval: 1.3, 7.6). BRCA mutation carriers with high serum E-2 level were significantly younger than the carriers with low serum E-2 level (31.4 +/- A 3.1 vs. 34.7 +/- A 4.9 years, p = 0.04). In this pilot study, we found an association between high basal serum E-2 levels and BRCA2 mutations. Our results suggest that increased production of E-2 may have a role in the pathogenesis of BRCA2-mutation-related breast cancer.