Objective: To examine cigarette smoking as a risk factor for different types of epithelial ovarian cancer.
Methods: We used data from the Cancer and Steroid Hormone Study, a multicenter, population-based, case control investigation. Cases were 447 women aged 20-54 years with diagnoses of epithelial ovarian cancer. Controls were 3868 women selected by random-digit dialing. Conditional logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs) as estimators of the relative risk of ovarian cancer. With age and study site as conditioning variables, OR point estimates were additionally adjusted for parity and use of oral contraceptives.
Results: The OR of mucinous epithelial ovarian cancer for women who had ever smoked was 2.3 (95% CI 1.4, 3.9) and for current smokers was 2.9 (95% CI 1.7, 4.9). The OR of mucinous tumors for current smokers was significantly elevated regardless of years since first cigarette or age at which women first smoked. The OR of mucinous tumors for current smokers increased slightly as cumulative pack-years of smoking increased, although the trend was not significant. Similar patterns of elevated risk were not observed among serous, endometrioid, or other histologic types. Odds ratio point estimates for former smokers were not significantly elevated for any histologic type.
Conclusion: Current cigarette smoking was a risk factor for mucinous epithelial ovarian cancer, but not other histologic types.