Objective: We conducted a population-based case-control study to investigate the association between hormone therapy (HT) and ovarian cancer incidence, and followed all these cancer cases to determine the association of HT use with ovarian cancer mortality.
Methods: Seven hundred fifty-one incident cases of invasive epithelial ovarian cancer aged 40-79 years were diagnosed in Massachusetts and Wisconsin between 1993-1995 and 1998-2001 and matched to similarly aged controls (n = 5,808). Study subjects were interviewed by telephone, which ascertained information on HT use and specific preparation, estrogen alone (E-alone) or estrogen plus progestin (EP). Ovarian cancer cases were followed-up for mortality through December 2005. Multivariate logistic regression was used to estimate odds ratios and 95% confidence intervals (CI) for ovarian cancer incidence, and Cox proportional hazards modeling was used to estimate hazard ratios and corresponding confidence intervals for ovarian cancer mortality.
Results: Ever use of HT was significantly associated with an increased risk of ovarian cancer (odds ratio 1.57, 95% CI 1.31-1.87). The excess risk was confined to women who used E-alone preparations (OR 2.33, 95% CI 1.85-2.95). No significant associations were detected between pre-diagnosis HT use and ovarian cancer survival.
Conclusions: Hormone therapy increases risk of ovarian cancer among E-alone users, but there is no substantial impact on survival after diagnosis.