Many epidemiological studies have linked the use of the intrauterine device with decreased risk of Endometrial Cancer. Tao MH, et al in China, studied 1204 patients with newly diagnosed endometrial cancer, compared with a cohort of 1212 healthy patients. Patients who developed endometrial cancer (485) had used IUDs for more than years, compared to 687 patients in the control group.

It is speculated that the reduction in endometrial cancer in patients with IUD is related to inhibition of the binding of estrogen and progesterone to the endometrial receptors, decreasing the concentration of receptor the number of nuclear endometrial cells, these changes can influence the activity of estrogen and progesterone which has protective effect at the level of the endometrium.
Continued use of TCu intrauterine device, after 6 months, induces a significant reduction in the mitotic index of endometrial cells, as well as reducing the concentration of estrogen receptors, but does not affect the levels of serum progesterone, estradiol or the concentrations of progesterone receptors, which could interfere with the protective effect of copper IUD in endometrial cancer. Other factors such as obesity, ethnicity, specially Hispanic or African American race, low socioeconomic status and / or the presence of chronic degenerative disease, play a crucial and defining role in the development of endometrial cancer. Of note, all these are modifiable factors, and 40% of obese women with endometrial cancer or endometrial hyperplasia, know that obesity is the determining factor for the development of this disease.