The issue is antioxidants and radiation. Most oncologists are told that antioxidants interfere with the killing effect of their chemotherapy or radiation therapy so they, in turn, recommend that patients receiving chemotherapy or radiation stop taking anti-oxidants.
For example, in collaborating with a conventional oncologist about the care of a patient headed for targeted radiation therapy for endometrial cancer, I received this response which discouraged the use of anti-oxidants while the patient underwent radiation therapy.
The subject of supplemental antioxidants with radiation and chemotherapy has gotten a lot of press. The human evidence, however, is quite definite that antioxidants will interfere with radiation and ros (reactive oxygen species) based chemotherapies some, but not all, of the time. Bairati et al is a great example of this principle. Unfortunately there is no mechanism to predict when these interactions will occur and when they will not. Since antioxidants are important nutrients for all humans, especially cancer survivors, we presumptively assume that an interaction can take place with patients receiving potentially vulnerable cancer treatments and then time the antioxidants based on the pharmacokinetics of both so that they do not interact.
Increasingly, however, there is good research suggesting there is an important argument to be made about supporting a patient receiving chemotherapy or radiation therapy antioxidants such as Co Q 10, vitamins A, C, D and E, as well as glutathione, n-acetyl cysteine, alpha lipoic acid, selenium, zinc and other nutrients. However many patients are stripped of these guardian angels when beginning conventional therapy for their cancer. So let’s look at the research and see what is reasonable.
Today, anyone can get on the internet and go to the government medical scientific data base called “PubMed” at http://www.ncbi.nlm.nih.gov/pubmed/ . I shared this question with my friend Dr. Joe Pizzorno and he reviewed the literature then offered the following report.
At http://www.ncbi.nlm.nih.gov/pubmed/ you can search combination terms like “selenium” and “cancer” or “vitamin C” and “cancer” . So let’s look at the terms “antioxidants cancer chemotherapy” and behold! It produces over 1,000 hits. Putting in the limits on the search to narrow it to human trials, we get a very interesting 146 hits. The terms are “Human and Abstract and Clinical Trial” . Looking more closely, we find only a handful, a bit over 40 actual intervention trials. So that is the collection of studies we need to consider in deciding whether the science supports using antioxidants while undergoing chemotherapy.
From the Research:
– “There was no difference in objective mucositis scores with a mean score of 0.2 with vitamin E and 0.3 with placebo.”
– “vitamin E effectively and safely protects patients with cancer from the occurrence of paclitaxel-induced peripheral nerve damage”
– “oral N-acetylcysteine reduces the incidence of oxaliplatin-induced neuropathy in colon cancer patients”
“CONCLUSION: These results do not support the concern that antioxidants might protect cancer cells from the free radical damage induced by chemotherapy. Larger trials are needed to demonstrate whether high-dose multiple antioxidants in conjunction with chemotherapy increase the response rates and/or survival time in advanced lung cancer.”
– “No significant differences were found between the two study groups with respect to these primary outcome measures. However, patients who achieved the highest plasma concentrations of the three antioxidant micronutrients had significantly less loss of high-tone hearing.”
– “we conclude that there are beneficial effects caused by ingesting selenium, as a supportive element in chemotherapy.”
– “Supplementation of patients receiving cisplatin chemotherapy with vitamin E decreases the incidence and severity of peripheral neurotoxicity.”
CONCLUSION: None of these studies reported impairment or improvement in clinical efficacy of the chemotherapy and most suggested some benefit in terms of reduced adverse drug reactions (ADRs) or commonly know as side-effects.
So we can conclude that, based upon a literature review, for selected chemotherapy drugs, some specific antioxidants appear to ameliorate their toxicity (lessen the side-effects!) This is not a blanket statement of safety and efficacy of antioxidants, but also looks like there is no documentation of harm or of interference with the intended killing effects of chemotherapy or radiation.
As with most of what we learn in science, more research would help to clarify the situation. However, in my clinic, I recommend that patients who undergo chemotherapy or radiation therapy also receive rescue doses of anti-oxidants subsequent to exposure to cancer treatments in order to bolster their native immune system and thereby optimize their outcomes.