Well, Looking for cures of cancer might be a good idea and a worthwhile endeavour. I mean why waste precious system resources to a project that was officially abandoned by the U.S. Government. Also, even i think its not useful. You might save some lives anyway by helping research on Cancer and other such things which might help the humanity more. Go here:
http://folding.stanford.edu/download.html Its called Folding@Home. Give it a try! Even i used to donate to Seti but after finding this , i thought i was wasting precious CPU power. Good luck!