The irregular tan mass filling the endometrial cavity and infiltrating into the myometrium of the uterus is an endometrial adenocarcinoma, seen to be moderately differentiated microscopically. Most patients with this neoplasm are 55 to 65 years of age, and rarely younger than 40 years. The major risk factor for this carcinoma stems from prolonged estrogen stimulation. Conditions that lead to increased estogenic exposure can produce endometrial hyperplasia, from which a cancer can arise. Anovulatory cycles, obesity, estrogen-producing ovarian tumors, low parity or nulliparity, and exogenous estrogen therapy can all increase the risk for endometrial adenocarcinoma in this manner. Hypertension and diabetes mellitus are also risk factors. Irregular postmenopausal bleeding may be the only sign, and the uterus may not be significantly enlarged. Most endometrial adenocarcinomas are confined to the uterus (Stage I) with a 5-year survival around 90%.