Changes in the cells of the uterus can lead to cancer. There are two primary types of uterine cancer. The most common type is endometrial carcinoma, which originates from the cells forming the inner lining of the uterus (the endometrium). The second primary type, uterine sarcoma, develops in the supportive tissues of the uterus, such as muscle and connective tissue. Additionally, a rarer type known as carcinosarcoma, which exhibits characteristics of both carcinoma and sarcoma, can also occur in the uterus.