The most common forms of uterine cancer arise from the endometrium. Among endometrial tumors, endometrioid adenocarcinomas are the most frequent subtype. Other types of endometrial cancers including uterine papillary serous carcinomas (UPSC) and clear cell carcinomas. Both of these types of cancers are more aggressive than endometrioid carcinomas.
Approximately 5% of uterine cancers arise from the muscular walls of the uterus. These tumors are known as uterine sarcomas. The common forms of uterine sarcoma are carcinosarcoma, leiomyosarcoma, and endometrial stromal sarcoma. Uterine sarcomas, though less common, tend to be aggressive tumors and account for a disproportionate number of deaths.