NCCN Soft Tissue Sarcoma Clinical Practice in Oncology Guidelines version 1.2005

This flow-chart guideline from the National Comprehensive Cancer Network deals with GIST as well as other sarcomas. It is a 49-page Adobe pdf document. For GIST, see especially the flow charts on pages 15-20 and the text on pages 37-39.
Free access via National Comprehensive Cancer Network website.
You must go through a series of steps at the NCCN website to access this document.
First link to NCCN
NCCN
Then click "NCCN Clinical Practice Guidelines in Oncology."
Then click "NCCN Complete Library of Clinical Practice Guidelines Online."
Scroll to the bottom of the "agreement" page and click "I agree."
On the next page scrool down to Cancer by Site and click "Soft Tissue Sarcoma" in the right-hand column.
This will begin downloading the Adobe pdf document for you to view or print.
If you get lost in those steps, here is a direct link.
Soft Tissue Sarcoma Guidelines v1.2005