Uterine sarcoma is a type of cancer that affects the uterus (womb). Uterine sarcomas start in tissues such as muscle, fat, fibrous tissue, and bone. They comprise less than four percent of uterine cancer cases. (Endometrial cancer is the most common type of uterine cancer, accounting for about 95 percent of uterine cancers. Other uterine cancers include various malignant tumors and uterine sarcomas.)
Uterine sarcomas are rare and fall into three main categories. Endometrial stromal sarcomas develop in the supporting connective tissue of the endometrium. These cancers are low-grade, with a good survival outlook. Undifferentiated sarcomas are aggressive and have a poor survival rate. Uterine leiomyosarcomas start in the muscular wall of the uterus known as the myometrium. There is a fourth type of uterine sarcoma that is actually a hybrid, called uterine carcinosarcoma. Uterine carcinosarcomas start in the endometrium and have features of both sarcomas and carcinomas.
Pelvic radiation, used to treat some forms of cancer, can increase the risk for uterine sarcoma (although its benefits in treating the initial cancer usually outweigh that risk). A secondary cancer may be diagnosed anywhere from 5 to 25 years after the radiation exposure. The only other known risk factor is race: uterine sarcomas are twice as common in African-American women as they are in Caucasian or Asian women.
The exact cause of uterine sarcoma is not known, and most cases cannot be prevented. Unfortunately, many uterine sarcomas are not noticeable until they reach an advanced stage. There are no current screening tests to detect uterine sarcomas in women without symptoms. The Pap test is very good at screening for cervical cancer, but cannot detect most uterine sarcomas.
Symptoms that may indicate uterine sarcoma include: abnormal bleeding or spotting, vaginal discharge, and pelvic pain or palpable mass in the pelvis. However, these symptoms are often evident of something other than uterine sarcoma, like an infection, non-cancerous or pre-cancerous changes in the uterus or endometrium, or endometrial carcinoma. A woman with those symptoms should see a gynecologist for further tests, including a tissue biopsy.
The tissue may be tested for estrogen receptors and progesterone receptors, which are found on many endometrial stromal sarcomas. Knowing which receptors particular cancer cells contain, will aid your physician in determining the drugs that will be most effective for treatment. It should be noted that tissue biopsies are not very useful in finding leiomyosarcomas, which are often only diagnosed after surgical removal.
Treatment will depend on the type and stage of the cancer, as well as the patient's age, general health, and other individual considerations. The typical treatment for uterine sarcoma is surgery. Since the goal is to remove all of the cancer, the procedure usually involves a hysterectomy (removal of the uterus and cervix); in some cases, the fallopian tubes, ovaries, and part of the vagina will also be removed. Lymph nodes will also likely be tested to determine whether the cancer has spread.
Various types of radiation may be given prior to or after surgery to shrink the tumor and lower the risk of recurrence. Radiation is also sometimes used as the primary treatment when surgery is precluded. Chemotherapy is also an option for some women. Finally, some women are treated with hormone therapy, but this is mainly used to treat patients with endometrial stromal sarcomas.