Uterine sarcoma is a cancer of the muscle and supporting tissues of the uterus (womb). Sarcomas are cancers that start from tissues such as muscle, fat, bone, and fibrous tissue (the material that forms tendons and ligaments). Cancers that start in epithelial cells, the cells that line or cover most organs, are called carcinomas.
More than 95% of cancers of the uterus are carcinomas. If a carcinoma starts in the cervix, it is called a cervical carcinoma. Carcinomas starting in the endometrium, the lining of the uterus, are called endometrial carcinomas. These 2 cancers are discussed in our documents Cervical Cancer and Endometrial Cancer. This document is about uterine sarcomas.
Most uterine sarcomas fall into 1 of 2 categories, based on the type of cell they developed from:
Endometrial stromal sarcomas develop in the supporting connective tissue (stroma) of the endometrium. These cancers are rare, representing a little over 1% of all uterine cancers. These tumors can be divided into 2 groups: low-grade and undifferentiated (high-grade). Low-grade endometrial stromal sarcomas tend to grow slowly - patients with these tumors have a better outlook than those with undifferentiated (high grade) tumors. Undifferentiated tumors are more aggressive and respond differently to treatment than low-grade tumors.
Uterine leiomyosarcomas start in the muscular wall of the uterus known as the myometrium. These tumors make up about 2% of cancers that start in the uterus.
Another type of cancer that starts in the uterus is called carcinosarcoma. These cancers start in the endometrium and have features of both sarcomas and carcinomas. They can be classified with uterine sarcomas, but many doctors now believe they are more closely related to carcinomas. These cancers are also known as malignant mixed mesodermal tumors or malignant mixed mullerian tumors. Uterine carcinosarcomas are discussed in detail in the American Cancer Society document about endometrial cancer.
Can Uterine Cancer be prevented? Most cases of uterine sarcoma cannot be prevented. Although pelvic radiation increases the risk of developing a uterine sarcoma, the benefit of pelvic radiation in treating other cancers far outweighs the risk of developing a rare cancer such as uterine sarcoma many years later.
Treatment is based on the type of tumor, and in many cases a combination of treatments is used. The effectiveness of the treatment depends on the number of factors including the type, size and location of the tumor.