IUD use and the risk of endometrial cancer.

Objective: Although the intrauterine device (IUD) is one of the most widely used forms of contraception throughout the world, its potential long-term effects on the uterus have not been thoroughly evaluated. This paper reports the long-term results of IUD use on the incidence of endometrial cancer.

Study Design: The data is part of a nationwide case-control, pilot study that was undertaken in order to evaluate the possible influence of ovulation induction drugs on the risk of endometrial cancer. The study included 128 living women 35-64 years old, with a histologically confirmed diagnosis of endometrial carcinoma. The controls were 255 women from the same dialing areas selected by random digit dialing. A multivariate logistic model, controlling for age, was used to assess the independent effects of factors found to be significantly associated with endometrial cancer on univariate analysis.

Results: The following parameters were found to be independently associated with endometrial cancer controlling for age: nulliparity OR=2.7 (95% CI 1.1-6.5, P=0.03); history of infertility OR=1.8 (95% CI 1.0-3.3, P=0.05); BMI>/=27 OR=2.3 (95% CI 1.4-3.8, P=0.001). The use of oral contraceptives and IUD were found to be protective; OR=0.29 and 0.37, respectively, (95% CI 0.14-0.61, P=0.001, 0.19-0.70, and 0.003, respectively).

Conclusions: IUD use may have a protective effect on endometrial cancer risk. The protective effect of IUD may be either, through the intense inflammatory response that leads to other lisosomal and inflammatory actions, which may include cells responsible for early elimination of hyperplastic endometrial epithelial cells or, the more complete shedding of the endometrium associated with IUD use may decrease hyperplasia of the endometrium, a known risk factor for endometrial carcinoma.