Not quite sure on the date of this posting but need to jump in anyway. As someone who has had GIST for 12 years now - 8 of them with the condition being controlled by Gleevac/glivec, my strong advice is - Take it!! And get your dad to a centre that specialises in GIST. Gleevac not working on a primary tumour is absolute nonsense. Pretty much back to front advice actually. Gleevac works for around 85% of Gist patients. When it does work it usually shrinks the tumour dramatically. Surgery can still be a good option, but the surgical outlook may well be very different , and not nearly so drastic, after shrinkage with Gleevac/Glivec.