I would see a naturopathic Doctors to assist the traditional medicine. Getting your food from real food sources is far better than supplements. Vitamin C and E seem to be particullary bad for treating cancer, but fruits and vegetables due help keep the immune system stronger. Their is a lot of info out their, but the most promissing work seems to come from high quantities of Cruciferious vegetables that have show good success in providing a poor environment for cancer to thrive in. I have read that black cohosh and CoQ10 have shown promise worth investigating. Broccoli sprouts has shown the most powerful cancer fighting effects and can also be purchased in a supplements. I was told by the Mayo Clinic to reduce processed sugar intake. Your primary goal is obviously to stay strong and keep your immune function strong to fight the cancer and chemo. Check out the Pub Med site and reliable research web sites.
Good Luck,