He started on it the same day as his first radiation treatment, he had to have 5 with the cyberknife procedure and I honestly think by taking it he had no side effects of the treatment, they said the tumor would look like a shriveled up grape afterwards, but they weren't expecting it to be gone....it was great watching their expressions. He still takes it since he's prone to cancer (has had it twice now) but he does 3 days on and 4 days off.