Yeah, I guess you're right, a lot of docs seem pretty down on supplements all together. I concur with the vitamin E caution, that's the main antioxidant that can interfere with radiation therapy to my knowledge. My suggestion if you take high doses of vitamins, and if you choose CyberKnife, is to stop taking high doses of antioxidants a couple weeks before treatment, and start back up a month after if you wish. I didn't even take a regular multivitamin for the three days of treatment, then started taking it again the day after. I did take my whey protein though. As for supplements that are said to increase the effects of radiation on tumor cells, of course there's glutathione (or glutamine) found in whey protein, also, believe it or not, caffeine is said to increase radiosensitivity in tumor cells, while protecting healthy cells. Caffeine has even been known to cause tumor cell apoptosis (cell death) by itself. But caffeine can contribute to swelling and cause headaches, so I avoided it for a couple months after my treatment. Other things that can inhibit tumor growth are ginseng, and even beer (it has to do with the hops). My doctor has a PhD in tumor biology, he told me the only thing in your diet that can possibly contribute to the growth of these tumors, would be hormones, like birth control, anabolic steroids, etc. But there isn't even any hard data on that yet.