You might want to read this:
http://www.integratedhealthclinic.co...hemo-Block.pdf
There are newer studies for individual supplements coming out every day. IMO, the only way to take supplements while receiving oncology drugs is to research each one with the specifc drugs you're taking.
When I started chemo, my cancer center's pharmacists reviewed my supplement list and recommended the discontinuation of several supplements. I was surprised by their choices, so I did some research of my own and discontinued a few more. Recently I read an article in which one of those supplements they had asked me to discontinue was beneficial during chemo. (Unfortunately, even though it was recent, I don't remember which one.)
The one thing I do want to specifically recommend is that if you decide to take B vitamins, it is best to choose a brand that contains methylfolate (Quatrefolic or Metafolin) instead of folic acid. Many people have a wonky gene for folate (MTHFR), and folic acid is unusable for them (so they end up with high blood levels, but to no good effect). There is some evidence that folic acid can cause breast cancer. See here:
http://www.ncbi.nlm.nih.gov/pubmed/19336565
My particular MTHFR mutation is somewhat rare, but it causes an increase in breast cancer in women who are 45-55. Unfortunately, most of us have a mutation in this gene, so it's best to avoid trouble.
You might want to check out Sarah Charles' website for information about the foods (and supplements) that are good and bad for breast cancer. I found it very useful as a starting point:
http://foodforbreastcancer.com/
As for the quality of supplements, you can subscribe to:
http://www.consumerlab.com/
The cost is around $30/year, and they present a new report each month. All the old reports are available on the website.
I take 30+ supplements a day. To address those you specifically mention, I take a low dose Vitamin A supplement three times a week (to make up the shortfall evidenced by my food diary). I take 500 mg of Vitamin C. I take no supplemental Vitamin E at all, although I did before cancer. Most of the Vitamin E studies aren't encouraging, and my food diary says I'm getting enough, so I'm content to leave well enough alone.
As I mentioned, I stopped some (those above and other antioxidants) during chemo (ACTH). *When I started Herceptin, I also restarted the discontinued supplements.* I'm more than one year out of chemo and almost five months from my last dose of Herceptin, and so far, I have no evidence of recurrence, so I don't think it's a big leap to the conclusion that the supplements I took did not interfere with treatment.