Abstract B60: Contraceptive methods and ovarian cancer risk among Chinese women: A report from the Shanghai Women Health Study

Abstract

Abstract Background: Oral contraceptive (OC) use is known to be associated with reduced ovarian cancer risk; associations with other contraceptive methods, such as intrauterine devices (IUD) and tubal ligation (TL), are less clear. The majority of studies conducted to date have used case-control designs; fewer cohort studies have been conducted, especially among Asian women. As contraception use is popular among Chinese women, and the use of different contraceptive methods differs from Western countries, differences in associations with ovarian cancer risk may exist. Methods: Data from the prospective Shanghai Women's Health Study (SWHS) was used to evaluate associations between different contraceptive methods and risk of ovarian cancer. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by Cox proportional hazards regression; models included adjustment for age, education, years of ovulation, body mass index (BMI), first-degree family history of cancer (yes/no), and regular physical activity within 5 years (yes/no). Results: A total of 164 ovarian cancer cases occurred among 70,349 women after an average follow-up time of 11.74 years. The majority of women had ever used any contraception (77.0%), including OC use (20.4%), contraceptive shots (2.6%), IUD use (55.6%) and TL (14.7%). Ever use of any contraception method was associated with a non-significant reduction in ovarian cancer risk (HR: 0.83, 95% CI: 0.58-1.19). Similarly, among users of contraception, women with durations of OC use longer than the median (≥2 years) tended to have lower ovarian cancer risk (HR: 0.60, 95% CI: 0.26-1.39), while women with durations of IUD use longer than the median (≥23 years) had significantly decreased ovarian cancer risk (HR: 0.48, 95% CI: 0.30-0.75). Conclusion: Longer durations of IUD use had beneficial effects on ovarian cancer risk among Chinese women. Due to the high prevalence and long duration of IUD use among Chinese women, and the protective association seen in this study, we estimate that approximately 20 ovarian cancer cases (12.0%) were prevented in this study population. Therefore, patterns of use of different contraceptive methods in China may contribute to the lower incidence of ovarian cancer observed in this country. Citation Format: Zhezhou Huang, Alicia Beeghly-Fadiel, Honglan Li, Wanqing Wen, Yutang Gao, Wei Zheng, Xiao-Ou Shu. Contraceptive methods and ovarian cancer risk among Chinese women: A report from the Shanghai Women Health Study. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr B60.