Use of hormone replacement therapy before and after ovarian cancer diagnosis and ovarian cancer survival

Use of hormone replacement therapy (HRT) has been hypothesized to affect survival of epithelial ovarian cancer (EOC). We studied 5-year survival in patients with invasive EOC and borderline ovarian tumors (BOT) according to HRT use before and after diagnosis in a prospective nation-wide cohort study of 799 women diagnosed with EOC (n = 649) and BOT (n = 150) aged 50-74 years in 1993-1995 in Sweden. Cox regression was used to obtain multivariate age-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Multivariate models included indicator variables for age, tumor stage, grade and histological subtype. After 5 years of follow-up, 45% of the patients with EOC and 93% of the patients with BOT were alive. For women with BOT there were no associations between HRT-use pre- or postdiagnosis and survival. There was no overall difference in 5-year EOC survival according to use HRT before diagnosis (multivariate HR = 0.83, 95% CI = 0.65-1.08), except for serous EOC (HR = 0.69, 95% CI = 0.48-0.98). Analyses of different HRT preparations, duration and recency of use did not reveal any variations in pattern of survival. We observed a better survival for EOC-patients who used HRT after diagnosis (multivariate HR = 0.57, 95% CI = 0.42-0.78). We conclude that HRT-use prior to diagnosis of EOC does not affect 5-year survival, except for a possible survival advantage in serous EOC. Women using HRT after diagnosis had a better survival than women with no use, but we cannot rule out that this latter finding may reflect a subtle selection process.