I took 8 weeks of radiation treatment two yrs after RP. My PSA rose 3 consecutive times to a Level of 0.19ng post RP. I elected the to have 68.8 Rads of I.M.R.T radiation to the prostate bed. I believe my Doc told me that they could get the radiation beam down to the size of 3 millimeters. That's a pretty small intensive beam, but invariably some of the beam will hit the Colon. I have 2 ea sunburn spots about 1/4" long by 14" wide on my colon. I've experienced some periodic light bleeding but nothing real bad. Some blood can be seen in the stool sometimes. I have also experienced some narrowing of the colon, which has not cause me any problems as of yet. As you know, all radiation treatments have side affects and latent affects. I'm 6yrs out from my treatments and i have had no real problems from radiation treatments and the best part is that my PSA is or has been undetectable! Hope this help, Joe