The Impact of Family History on Ovarian Cancer Risk

Abstract

To estimate the relative risks and population attributable risks of ovarian cancer associated with family histories of cancer at several sites. A matched case-control analytic study (662 cases, 2647 controls), employing the Utah Population Database, a genealogy of approximately 1 million individuals linked to cancer incidence data from the Utah Cancer Registry. Family history was assessed using kinship order and a kinship-weighted familial standardized incidence ratio statistic. Family histories of ovarian, uterine, breast, and pancreatic cancer were significantly associated with increased risk of ovarian cancer. The relative risk of ovarian cancer was 4.31 (95% confidence interval [CI], 2.35 to 7.90) for women with a first-degree relative with ovarian cancer, 2.12 (95% CI, 1.19 to 3.78) for women with an affected second-degree relative, and 1.48 (95% CI, 0.98 to 2.24) for women with an affected third-degree relative. The odds ratio (OR) was 2.06 (95% CI, 1.44 to 2.93) for those with the highest familial standardized incidence ratio. No age differences were observed between cases with and without a family history of ovarian cancer. There was substantial heterogeneity of family history effects by cell type. Increased parity was not protective among women with a strong family history of cancer at the sites studied (OR, 1.11; 95% CI, 0.38 to 3.26), although it was protective among women without a family history of these cancers (OR, 0.29; 95% CI, 0.11 to 0.62). The risk of ovarian cancer was substantially increased among women with family histories of ovarian, uterine, pancreatic, and, to a lesser degree, breast cancer. Among women with family histories of any of these cancers, the risk of ovarian cancer is not diminished by high parity.