antioxidant supplements differ--some may decrease chance of recurrence, some increase

[ElaineM]

I look up interactions between whatever conventional medicines I am taking and what supplements I am taking.
There are several places one can look on the internet, but I find that www.drugs.com has a pretty good database of conventional medicines and supplements.
All we have to do is to type in the names of the drugs and supplements we are taking and click. A list of possible interactions will come up along with possible food interactions.
It could be that vitamin C and vitamin E have different interactions with different drugs, therefore affecting the success or failure of those drugs and eventually affecting survival of the people who are taking those drugs and/or supplements.
Doctors should check for these things, but sometimes they don't know either. Pharmacists are sometimes better than doctors when it comes to checking for drug interactions or drug and supplement interactions.