Age-specific familial risks in ovarian cancer have not been assessed by histologic types of medically verified cancers. We used the nationwide Swedish Family-Cancer Database on 10.2 million individuals and 19,175 invasive and 3,436 borderline ovarian cancers to calculate, by affected family members, standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for familial ovarian cancer in 0-66 year old daughters. SIRs for all invasive ovarian cancer were 2.68 (95% CI 2.22-3.21) by ovarian cancer in mother, 2.94 (1.40-5.94) by an affected sister and 24.03 (6.12-74.46) by both an affected mother and sister. The population-attributable fraction from mothers was 2.52%. Seropapillary cystadenocarcinoma showed the highest familial risk, but the effect of histopathol subtype could not be fully assessed because of lack of data in probands. Age-specific data showed some early-onset components and an unusual maximal incidence in the 40s. A comparison to an earlier study on BRCA1/2 mutation analysis and relative risks of ovarian and breast cancer suggests that these mutations could account for 26% of the familial aggregation of ovarian cancer. Histopathology and age of onset appear to be important attributes of familial ovarian cancer, suggesting that further gene identification efforts should target a specific histopathology in early-onset patients.
Copyright 2003 Wiley-Liss, Inc.