Intrauterine device use and endometrial cancer risk

Background. Because intrauterine devices (IUD) invoke acute and chronic inflammatory responses in the endometrium, it is possible that prolonged insertion of an IUD could induce endometrial cancer. Methods. We examined the relation between use of an IUD and endometrial cancer risk using data from a multicentre case-control study involving 405 endometrial cancer cases and 297 population controls. Results. A total of 20 (4.9%) cases and 34 (11.4%) controls reported any use of an IUD. After adjustment for potential confounders, IUD use was not associated with an increased risk of endometrial cancer (RR = 0.56 for ever use; 95% CI : 0.3-1.0). Little reduction in risk was observed among women who last used an IUD within 10 years of the index date (RR = 0.84; 95% CI :0.3-2.4) but risk was decreased among women who used an IUD in the more distant past (RR = 0.45; 95% CI :0.2-1.0). Risk did not vary consistently with number of years of IUD use or with years since first use. Risk was not increased among women who used inert devices (RR = 0.46; 95% CI :0.3-3.6) or those who used devices containing copper (RR = 1.08; 95% CI : 0.1-3.6). Conclusion. These data are reassuring in that they do not provide any evidence of an increased risk of endometrial cancer among women who have used IUD.