<b>Does STI-571 work against all GIST tumors?</b><br> No. In early Clinical Trials, it seems to be effective in shrinking tumors between 80% to 90% of the time. 

<b>How fast does STI-571 work against GIST tumors?</b><br> Generally, significant shrinkage is being seen within 30 days. 

<b>What is the c-kit test?</b><br> It is a test for CD117, or c-kit, a protein on the surface of the cell membrane.

<b>What is GIST?</b> 
A gastrointestinal primary tumor, Gastro Intestinal Stromal Tumor, considered LMS, but descended from a slightly different smooth muscle cell. All leiomyosarcomas show markers for smooth muscle (ie actin), but GIST arises from a specialized smooth muscle cell called Interstitial Cell of Cajal.  If you have GIST, find out if you are c-kit positive.  If so, you are a candidate for STI-571 should the need arise.                 

<b>How do I know if I am c-kit positive?</b>
A slide from your tumor is stained/tested and looked at under the microscope by a pathologist. 

<b>Does it matter if the tumor slide is from my primary tumor or from one of my mets (secondary tumor)?</b>
No.  But it needs to be a good sample of the tumor, not from an area that is necrotic.

<b>How do I get my tumor tested?</b>
The original laboratory that reported on your LMS will have the tumor kept there.  They can prepare new slides for a test.  It is suggested that you have the test done at a laboratory that does a lot of c-kit tests...like a sarcoma center laboratory.

<b>Is c-kit [CD117] the only indication that STI-571 might work?</b>
A tumor needs to be positive for c-kit, OR Abl, since these are the known targets of STI-571.  Abl is related to the Philadelphia chromosome, and is not relevant to LMS.  The PDGFr [platelet derived growth factor] is another test that can be done on your tumor for possible indication of a trial of STI-571.

<b>Is the c-kits test 100% reliable? </b>
No. No test is 100% reliable and c-kit test results can sometimes be false positive or false negative.  

<b>If my primary tumor was not in the gastrointestinal area (e.g. a uterine tumor), can it still be c-kit positive?</b>Anything is possible, but that is unlikely. 

<b>What does it mean, then, if a uterine primary tests c-kit positive?</b>
It means that it is probably a false positive.  It can be re-tested.                          

<b>Will STI-571 work against leiomyosarcomas that are not c-kit positive?</b>
Probably not, but the European trials will be testing that by offering STI-571 to a small number of c-kit negative sarcoma patients. 

<b>Is STI-571 a type of chemotherapy?</b>
No, it is not. Chemotherapy drugs are cytotoxics and they kill dividing cells with little regard for whether or not they are cancerous. STI-571, or Glivec, is a member of a new class of drugs called cytostatics--they are designed to home in on cancer cells without harming healthy ones. 

<b>Does that mean that the side effects of STI-571 are less than those of traditional chemotherapy?</b>
Generally yes--a lot less. 

<b>My doctor knows that I am c-kit positive but wants to do surgery anyway. What should I do?</b>
Unless you are in a life threatening situation, you should consult a sarcoma specialist about STI-571 as an alternative. 

<b>My doctor knows that I have GIST (i.e., am c-kit positive) but wants to treat me with traditional chemotherapy anyway. What should I do? </b>
Get another doctor, preferably a sarcoma oncologist specialist. 

<b>Should I trust the information above? </b>
You should always do your own research and consult with your own physician. 

The author of this question and answer series is not a physician and is simply an informed lay person trying to share his understanding of a complicated area. In doing so, the answers tend to be somewhat simplistic and may not always be completely accurate. In addition, keep in mind that the STI-571--GIST trials are very recent and still involve small numbers of patients. The author only has access to the early trial results of a small subset of trial patients who are members of the Life Raft Group--they may or may not be representative of the trial group at large. 

<b>Where can I get more information?  </b>

See the Article-Jerry &amp; Norman at: http://www.acor.org:/lrg/ 