It is of overwhelming importance, if your LMS arises in the gastrointestinal tract that it be tested for cKit [CD117]. If your tumor is positive for this protein, you probably have GIST [GI Stromal Tumor] and not GI LMS. GIST used to be considered a kind of GI LMS, but actually is a different tumor. GIST was extremely unresponsive to chemo and radiation, but the presence of this protein opens up the opportunity to use a new effective designer drug treatment. The drug is known as STI-571 or Gleevec [US trade name] or Glivec [worldwide trade name].

Gleevec works in GIST because cKit is the protein driving reproduction, and throwing a monkey wrench at it stops the tumor from growing. 

Gleevec's possible use as an adjunctive anti-angiogenesis agent with other chemotherapy agents, or its use as a sole agent in other cKit positive sarcomas, is being investigated in various clinical trials. 

Gleevec is not effective in LEIOMYOSARCOMA tumors that are ckit positive, because LMS tumor reproduction is not being driven by the ckit. However, LMS tumors that are PDGFr positive might respond to Gleevec. There is just not a reliable commercial test for PDGFr at this time. Gleevec is not a drug of first choice for LMS. It is however, a drug of first choice for GIST.