There is no firm data on this topic, but in general colon cancers are not that radiosensitive and for positive margins, with no other evidence of tumor, one should go to a high dose.  Ideally, if you know from preoperative scans that the margin is likely to be close or positive I would recommen...

I agree with @Joel E. Tepper.  My initial target volume (for 45 Gy) would depend on the preoperative findings. An advanced distal sigmoid colon cancer can involve structures in the true pelvis and therefore access much of the same nodal stations as a rectal cancer.  Otherwise, I would targ...