A leiomyosarcoma is one of a family of cancers called soft tissue sarcomas.
The soft tissue sarcomas are a group of cancers which develop from a number of different supportive tissues in the body including fibrous tissue, muscle, ligaments, tendons and fat.
Soft tissue sarcomas are rare. They make up less than 1% of all cancers, with only about 1200 new cases being diagnosed each year in the United Kingdom. Relatively speaking, they are actually more common in children than adults, making up about 8% of all cancers in those under the age of 15.
Soft tissue sarcomas can spread to other parts of the body by sending tiny clumps of tumour cells into the blood stream. The commonest site of spread for these cancers is to the lungs although leiomyosarcomas which develop in the digestive system have a tendency to spread to the liver.
Over the years more than 60 different types, or subtypes, of soft tissue sarcoma have been identified. As the group of tumours as a whole are quite rare this means that some forms of the condition are very very rare indeed. The large number of different types has also lead to problems in classifying the soft tissue sarcomas. Most have names based on the type of normal cell from which the cancer might have started but for some soft tissue sarcomas there does not seem to be any equivalent normal cell and so special names have been given to these tumours. Leiomyosarcomas are so-called because they arise from cells very similar to those found in a type of muscle tissue called smooth muscle.
Smooth muscle is the muscle tissue found in the walls of muscular organs like the heart and stomach as well as the walls of blood vessels throughout the body. This means that leiomyosarcomas can develop at any site in the body. Common sites for leiomyosarcomas are the uterus and the digestive system, particularly the stomach. Leiomyosarcomas of the digestive system are sometimes confused with gastrointestinal stromal tumours. This is a very important distinction as there is new and effective treatment for many gastrointestinal stromal tumours known as Gleevac or STI571.
Leiomyosarcomas usually start as a fairly rapidly growing, painless, swellings in the wall of an organ or a blood vessel. Generally the tumours cause few other symptoms and can often become quite large before they are diagnosed.
Like most other soft tissue sarcomas the treatment of a leiomyosarcoma is surgery, wherever possible, to remove the growth. This may be followed by a course of radiotherapy to reduce any chance of the cancer coming back. Chemotherapy is also recommended for some leiomyosarcomas arising in the uterus but those tumours developing in the digestive system tend to be less sensitive to chemotherapy.