Antioxidants during radiation?
Elizabeth Adler wrote:
I've been wondering about taking antioxidant vitamins during radiation therapy. I can imagine both good (prevention of possible unfortunate side effects) and bad (protection of the lymphoma from being destroyed by the radiation) effects of doing this. Has anyone come across any studies that address this issue?
I'm not aware of any studies, but generally I've heard knowledgble people say no. The reasoning is - radiation causes DNA damage, and cells respond by a process called apoptosis or "programmed cell death." That is, they embark on a biochemical pathway or cascade of reactions ultimately resulting in their demise - they commit suicide. Apoptosis utilizes free radicals as one of it's mechanisms, and antioxidants could interfere with this. So one should grin and bear it - trying to ease side effects in this way could make it easier for the cancer cells to survive the radiation. Incidently, one of the mediators of programmed cell death in response to DNA damage is p53. Therefore, a p53 loss (mutation) aborgates one of the apoptotic pathways and such cells are more resistant to radiation (and chemo). It's actually more complicated that this, as there are redundant ways to achieve programmed cell death, many of which aren't understood (and I'm sure, not even known), but one shouldn't do anything to give the little buggers an edge.
I don't have a study to quote but I'm pretty sure my radiologist nurse specifically mentioned no antioxidants during therapy.
Good luck, Al (who goes in for radiation simulation tomorrow)
Thanks for your really thoughtful and knowledgeable response to my inquiry. You've very clearly and lucidly stated the thought that went into my vague "bad (protection of the lymphoma ..." comment. And if the only side effects were fatigue, skin irritation and the like, there'd be no doubt in my mind as to the best course of action. But ... free radicals produced by ionizing radiation may also be involved in DNA damage leading to the generation of secondary cancers. And antioxidants could protect against this. If both factors are equal, it doesn't make a whole lot of sense to attempt to protect oneself from a secondary cancer one _may_ incur twenty years from now at the expense of possibly protecting one's current _known_ lymphoma from eradication. However, it had occurred to me that, given that cancers likely do have unusual pathways at their disposal, they might be less sensitive to antioxidant levels than normal cells. In this case, the benefits of antioxidants could outway the disadvantages.
But the biology is so complex (and poorly understood) that something that makes a certain amount of sense in theory could well prove competely incorrect in fact. Which is why I'm still hoping that someone on the list may be familiar with a study on this. I haven't been able to find anything on Medline, but there's been sufficient interest in antioxidant vitamins that I'd be surprised if no one had looked at it.
If no new information turns up, I'll follow Al's nurse's advice (Good luck on your simulation, Al!, and thanks for passing this on) and avoid the antioxidants. And, after your next post, I'm not going to worry too much about it. It got into the 50's today, and I went for a walk. And now, I think I'll go meditate.