Endometrial carcinomas, which start in the cells of the inner lining of the uterus (the endometrium). Nearly all cancers of the uterus are this type. These cancers are the focus of the remainder of this information. Endometrial carcinomas can be divided into different types based on how the cells look under the histologic types. These include: Adenocarcinoma Carcinosarcoma Squamous cell carcinoma Undifferentiated carcinoma Small cell carcinoma Transitional carcinoma The most common type of adenocarcinoma is known as endometrioid cancer. Endometrioid cancers are made up of cells in glands that look much like the normal uterine lining (endometrium).