Women from site-specific hereditary breast cancer families who carry a BRCA1 or 
BRCA2 mutation are at increased risk for ovarian cancer. It is less clear, 
however, whether individuals from hereditary breast cancer families who do not 
carry such a mutation are also at increased ovarian cancer risk. To determine 
whether women from BRCA mutation-negative hereditary breast cancer families are 
at increased risk for ovarian cancer, 199 probands from BRCA mutation-negative, 
site-specific breast cancer kindreds who consented to prospective follow-up at 
the time of genetic testing were identified. The incidence of new breast and 
ovarian cancers in probands and their families since receipt of their genetic 
test results was determined by questionnaire. The expected number of cancers and 
standardized incidence ratios (SIRs) were determined from age-specific cancer 
incidence rates from the Surveillance, Epidemiology, and End Results (SEER) 
program by using the method of Byar. All statistical tests were two-sided. 
During 2534 women-years of follow-up in 165 kindreds, 19 new cases of breast 
cancer were diagnosed, whereas only 6.07 were expected (SIR = 3.13, 95% 
confidence interval [CI] = 1.88 to 4.89; P < .001), and one case of ovarian 
cancer was diagnosed, whereas only 0.66 was expected (SIR = 1.52, 95% CI = 0.02 
to 8.46; P = .48). These results suggest that women from BRCA mutation-negative, 
site-specific breast cancer families are not at increased risk for ovarian 
cancer.