The usual garbage you hear from hard-wired mainstream oncologists is that vitamin C is "dangerous". That's because (they claim) it interferes with chemo and stops it working. They just ignore the fact that chemo doesn't work either on people NOT taking vitamin C!
The scientific truth is antioxidants and other nutrients do not interfere with chemotherapy or radiation therapy and can increase survival.
"At high concentrations, ascorbate does not interfere with chemotherapy or irradiation and may enhance efficacy in some situations . . . Meta-analyses of clinical studies involving cancer and vitamins also conclude that antioxidant supplementation does not interfere with the efficacy of chemotherapy." 
This is to counter and evil and stupid 2008 study from Sloan-Kettering. The study was performed on mice (so what, you ask?) The underperforming "researchers" didn't seem aware that mice—like most animals—make their own onboard vitamin C. The equivalent, in human terms, of about 10 grams a day (10,000 mg)!
Yet, the researchers claimed that supplementing the mice with as little as 100 mg of vitamin C could "blunt" the effectiveness of chemo. Well, chemo doesn't have any effectiveness, but we'll let that pass for another day.
Their claims were trumpeted far and wide in the media, which loves to run stories that vitamin C is dangerous! They then ignored the absurdity that in mice taking 10,000 mg a day, the chemo was "effective", yet if the mice had 10,100 mg, chemo was spoiled.
It doesn't make any sense.
There Are Real Benefits
The important story is that vitamin C greatly benefits cancer patients, quite aside from any cancer cell killing it does:
- Vitamin C reduces the side effects of chemo.
- Vitamin C reduces the side effects of radiation.
- Vitamin C reduces post-surgical inflammation and infection, and reduces healing time.
Cancer patients can and should take antioxidants and other nutritional supplements while undergoing radiation therapy or chemotherapy. Vitamin C and other nutrients reduce side effects, and actually improve the results with both chemo and radiation.
Radiation Oncologist, Victor Marcial-Vega, MD, always administers high-dose-vitamin-C-therapy to his cancer patients. He says, "Vitamin C has two effects; It increases the beneficial effects of radiation and chemotherapy and decreases the adverse effects. Once you start using IV vitamin C, the effect is so dramatic that it is difficult to go back to not using it.
"Vitamin C increases the beneficial effects of radiation and chemotherapy and decreases the adverse effects. But this is not a subtle effect, is not 15-20%, it's a dramatic effect. Once you start using IV vitamin C, the effect is so dramatic that it is difficult to go back to not using it."
So, if you are facing any kind of malignancy, plonk this article down on your doctor's desk and DEMAND he read it properly, including looking up the references.
And, of course, you can always get yourself a copy of my cancer alternative therapies "Bible"
When facing an oncologist, don't take no for an answer. And don't accept B*S*, like "It's not allowed." It's in the literature! In Japan, for example, IV vitamin C is now a standard cancer treatment—and rightly so.
I was doing it 20 years ago… It's a wonder therapy!
But let's hope you never need it."
3. Simone CB 2nd, Simone NL, Simone V, Simone CB. Altern Ther Health Med. 2007;13:22-28. https://www.ncbi.nlm.nih.gov/pubmed/17405678 See also: Block K, Koch AC, Mead MN, Tothy PK, Newman RA, Gyllenhaal C. Impact of antioxidant supplementation on chemotherapeutic toxicity: a systematic review of the evidence from randomized controlled trials. [Int J Cancer. 2008;123:1227-1239. doi:10.1002/ijc.23754. https://onlinelibrary.wiley.com/doi/epdf/10.1002/ijc.23754]4 . https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3751545
5. Chatterjee IB, Majumder AK, Nandi BK, Subramanian N. Synthesis and some major functions of vitamin C in animals. Ann N Y Acad Sci. 1975 Sep 30;258:24-47