Intravaginal estrogen creams and endometrial cancer: no causal association found.

In two case-control studies of estrogens and endometrial cancer, women were asked about previous use of intravaginal estrogen creams. In a set of cases and controls chosen by conventional procedures from a tumor registry, the odds ratio was 0.90. In an alternative set of cases and controls who had all received dilatation and curettage or hysterectomy, the odds ratio was 0.82. Despite the reported relationship between oral estrogens and endometrial cancer and although intravaginal estrogen creams are readily absorbed by the vaginal mucosa, we detect no causal association for their use.