Familial ovarian cancer: a population-based case-control study.

Data from a multicenter population-based case-control study were analyzed to assess the degree of aggregation of ovarian cancer in families. Included as cases were 493 women aged 20-54 who had been newly diagnosed with epithelial ovarian cancer. The frequency with which cases reported a family history of ovarian cancer was compared with the frequency for a group of 2,465 controls selected by random digit dialing. The odds ratios for ovarian cancer in first- and second-degree relatives were 3.6 (95% confidence interval (Cl) 1.8-7.1) and 2.9 (95% Cl 1.6-5.3), respectively, compared with women with no family history of ovarian cancer. The null hypothesis of no association was excluded on both the maternal and paternal sides of the families studied. Ovarian cancer in relatives was reported by women with malignant lesions but not by women with borderline lesions. These results did not seem to be attributable to the possible confounding effects of any of several covariates or to errors in reporting family history of ovarian cancer.