BACKGROUND: Mutations in BRCA1/2 genes confer ovarian, alongside breast, cancer 
risk. We examined the risk of developing ovarian cancer in BRCA1/2-positive 
families and if this risk is extended to BRCA negative families.
PATIENTS AND METHODS: A prospective study involving women seen at a single 
family history clinic in Manchester, UK. Patients were excluded if they had 
ovarian cancer or oophorectomy prior to clinic. Follow-up was censored at the 
latest date of: 31/12/2010; ovarian cancer diagnosis; oophorectomy; or death. We 
used person-years at risk to assess ovarian cancer rates in the study 
population, subdivided by genetic status (BRCA1, BRCA2, BRCA negative, BRCA 
untested) compared with the general population.
RESULTS: We studied 8005 women from 895 families. Women from BRCA2 mutation 
families showed a 17-fold increased risk of invasive ovarian cancer (relative 
risk (RR) 16.67; 95% CI 5.41 to 38.89). This risk increased to 50-fold in women 
from families with BRCA1 mutations (RR 50.00; 95% CI 26.62 to 85.50). No 
association was found for women in families tested negative for BRCA1/2, where 
there was 1 observed invasive ovarian cancer in 1613 women when 2.74 were 
expected (RR 0.37; 95% CI 0.01 to 2.03). There was no association with ovarian 
cancer in families untested for BRCA1/2 (RR 0.99; 95% CI 0.45 to 1.88).
DISCUSSION: This study showed no increased risk of ovarian cancer in families 
that tested negative for BRCA1/2 or were untested. These data help counselling 
women from BRCA1/2 negative families with breast cancer that their risk of 
invasive ovarian cancer is not higher than the general population.