The American Cancer Society describes uterine sarcoma as cancer that starts in the muscle and tissues that support the uterus. This differs from endometrial cancer, which starts in the lining of the uterus called the endometrium. Once uterine sarcoma is diagnosed, it is staged based on the spread and extent of the cancer. There are four stages, from Stage I to IV, in ascending severity and extent of disease.
The Women's Cancer Network describes three types of uterine sarcoma: endometrial stromal sarcoma, uterine leiomyosarcoma and uterine carcinosarcoma. Endometrial stromal sarcoma originates in the tissues that support the endometrium, which is the lining of the uterus. These tissues are called the stroma. Uterine leiomyosarcoma starts in the wall of the uterus, which is a muscle called the myometrium. Although this is cancer is rare, it is not easily found until surgery because a uterine biopsy does not take tissue from this area. Uterine carcinosarcoma consists of cancer that is a mixture of sarcoma and carcinoma, which affects the lining of organs; this is not diagnosed as often as the two previous kinds.
There are two sub-stages of Stage III uterine sarcoma. According to the National Cancer Institute, Stage III uterine sarcomas have spread past the uterus and cervix, but are contained within the pelvis. In Stage IIIA, the cancer has spread to the outer layer of the uterus, the tissues around the uterus, or the peritoneum, which is the lining on the abdominal wall. In Stage IIIB uterine sarcoma, the cancer has spread to lymph nodes in the pelvis and/or near the uterus. There is no cancer in distant organs.
The last stage of uterine sarcoma is also broken down into two sub-stages. The American Cancer Society describes Stage IVA uterine sarcoma as cancer that has spread to the rectum or bladder. Lymph nodes may also be cancerous, but there is no spread to distant organs. Stage IVB consists of uterine sarcoma that has spread to organs far from the uterus, typically the bones or lungs; it may have also spread to distant lymph nodes.
Treatment by Stage
Surgery, usually consisting of removal of the uterus and cervix, ovaries and fallopian tubes and some surrounding lymph nodes, is a typical treatment for Stage III uterine sarcomas, according to the National Cancer Institute. Clinical trials of surgery followed by various treatment modalities like pelvic radiation or chemotherapy may also be treatment options. There is no standard treatment protocol for Stage IV uterine sarcoma, so the National Cancer Institute suggests clinical trials of chemotherapy for patients at this stage.
For leiomyosarcoma, the American Cancer Society says that Stage III cancer carries a five-year survival rate of 28 percent, and for Stage IV the five-year survival rate is 15 percent. Endometrial stromal sarcoma has slightly better survival rates, with the five-year survival rate for Stage III being 64 percent and Stage IV being 37 percent.