What is Leiomyosarcoma?

Leiomyosarcoma is a type of cancer that develops in smooth muscle cells. It is an extremely rare type of cancer; in the Unites States, for example, the frequency of leiomyosarcomas is just 1.4 cases per 100,000 people. The prognosis for this type of cancer is generally poor, with the five-year survival rate ranging from 30 percent to 90 percent, depending on several factors.

Smooth muscle cells are found in involuntary muscles, which are located in many parts of the body, including the stomach, intestines, uterus, skin and blood vessel walls. Involuntary muscle tissue is so-called because it is not possible to cause movement of these muscles; movement of these muscles occurs automatically in response to bodily stimuli. The most common locations for leiomyosarcomas to develop are the gastrointestinal tract and the uterus.

The cancer can develop in multiple locations, so the symptoms of leiomyosarcoma are highly variable. All types can cause pain, swelling and the formation of a lump at the point of origin, although the lump is not always noticeable right away. A uterine lump or gastrointestinal lump might not be noticeable immediately, whereas a lump on the skin will be noticed much sooner. When the cancer develops in the gastrointestinal tract, it might cause abdominal bloating, gas, digestion problems or blood in stool. In the case of uterine cancer, the main symptom is often abnormal vaginal bleeding.

For many people with this cancer, bleeding is the main symptom. Bleeding might be slow and steady or intermittent. In some cases of leiomyosarcoma bleeding can become hemorrhagic. When this occurs, emergency medical treatment is required, generally involving one or more blood transfusions. As many as half of those with hemorrhagic bleeding might also require emergency surgery to locate and stem the bleed.

Leiomyosarcoma is curable only in cases where surgery to remove the cancer is a viable treatment option. If the entire tumor, in addition to local lymph nodes, can be removed successfully, a cure is possible as long as the cancer has not spread beyond the closest lymph nodes. This surgery generally is followed by chemotherapy or radiotherapy to kill any cancer cells remaining. Chemotherapy and radiation therapy are not effective as standalone treatments, however.

Even though surgery can successfully treat the cancer, it is not a guaranteed cure. Recurrence of the cancer tends to be probable rather than possible, and because of the rarity of leiomyosarcomas, a standard for follow-up treatment has not been established. Generally, a patient who has been treated for this disease will undergo yearly scans and blood tests to check for cancer recurrence.