I-P 6 and other supplements

My husband just finished radiation and chemo therapy (3 days ago) at the Mayo clinic.  Surgery is scheduled to occur in a month for esophageal cancer.

My question is - when is it safe to take I-P 6 and other supplements that may provide additional nutritional support.  I understand that the chemo and radiation effects "peak" in two weeks and I do not want to interfere with that.  Would taking supplements now - negatively affect the chemo and radiation work? 

That is as very controversial topic.  My suggestion is to do a thorough web search on the issue.

I've read that IP6 helps revert cancerous cells back to normal.  I'm not sure how this would affect radiation therapy, which is trying to kill the cells.