Impact of levonorgestrel releasing intrauterine system use on the cancer risk of the ovary and fallopian tube
Abstract Background: Levonorgestrel releasing intrauterine system (LNG IUS) is used for contraception and heavy menstrual bleeding. A long term hormone therapy can modify the risk of gynecologic cancers. Little is known about the impact of LNG IUS use on the risk for invasive and borderline ovarian tumor subtypes or for primary fallopian tube carcinoma. We examined the associations of LNG IUS use with these tumors. Material and methods: We identified from the national Medical Reimbursement Registry of Finland the women aged 30 49 years who had used LNG IUS for menorrhagia in 1994 2007, and from the Finnish Cancer Registry ovarian cancers and primary fallopian tube carcinomas diagnosed before the age of 55 and by the end of 2013. Results: A total of 77 invasive ovarian cancers and seven primary fallopian tube carcinoma cases were diagnosed in a cohort of 93 843 LNG IUS users during the follow up of 1 083 126 women years. The LNG IUS users had decreased risk for both invasive ovarian cancer [standardized incidence ratio (SIR) 0.59, 95% confidence interval (CI) 0.47 0.73] and for borderline ovarian tumors (SIR 0.76, 95% CI 0.57 0.99) as compared to the background population. The risk of primary fallopian tube carcinoma was not increased (SIR 1.22, 95% CI 0.49 2.50) Decreased risks for mucinous (SIR 0.49, 95% CI 0.24 0.87) endometrioid (SIR 0.55, 95% CI 0.28 0.98) and serous ovarian carcinomas (SIR 0.75, 95% CI 0.55 0.99) were seen in LNG IUS users. Conclusions: LNG IUS use associated with decreased risk for both invasive and borderline ovarian tumors. The incidence of primary fallopian tube carcinoma did not significantly differ between LNG IUS users and the background population.
Acta oncologica