Ovarian cancer risk associated with varying causes of infertility

OBJECTIVE: To evaluate the risk of ovarian cancer as related to underlying causes of infertility. DESIGN: Retrospective observational cohort study. SETTING: Five large reproductive endocrinology practices. PATIENT(S): A total of 12,193 women evaluated for infertility between 1965 and 1988. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Ovarian cancer ascertained through 1999. RESULT(S): With 45 identified ovarian cancers, this cohort of infertility patients demonstrated a significantly higher rate of ovarian cancer than the general female population (standardized incidence ratio [SIR] = 1.98; 95% confidence interval [CI], 1.4-2.6). The risk was higher for patients with primary infertility (SIR = 2.73) than for those with secondary infertility (SIR = 1.44), and it was particularly high for patients who never subsequently conceived (SIR = 3.33). Women with endometriosis had the highest risk (SIR = 2.48; 95% CI, 1.3-4.2), with a further elevated risk among those with primary infertility (4.19, 2.0-7.7). Comparisons among the infertile women, which allowed calculation of rate ratios (RRs) after adjustment for multiple factors, also showed links with endometriosis. Compared with women with secondary infertility without endometriosis, patients with primary infertility and endometriosis had a RR of 2.72 (95% CI, 1.1-6.7). CONCLUSION(S): Determination of ovarian cancer risk should take into account the type of infertility (primary vs. secondary) and underlying causes. Further study of endometriosis may provide insights into ovarian carcinogenesis.