Should chemotherapy patients take antioxidant supplements? Because many of the drugs used in chemotherapy could be classified as “oxidants”, generating free radicals for the deliberate purpose of causing cell damage (the intended target for this damage is cancer cells, of course), there is therefore medical concern that the effectiveness of some types of chemotherapy could be hampered if antioxidants were taken at the same time.¹ A recent literature-search study found evidence supporting the use of antioxidant supplements during chemotherapy treatments.

The study involved five different electronic databases including MEDLINE, using search terms related to cancer treatments and antioxidants. Databases were searched from their inception up until the end of December, 2006 and foreign medical studies were included. Only randomized, controlled clinical trials which reported survival data or tumour response were included. Studies which used whole herbs and mixtures were excluded because of potential non-antioxidant properties. Of 845 references screened, 19 studies with a combined total of 1554 patients met the criteria for inclusion in the final review summary.  The 19 studies represented over 15 different cancers in various stages, 17 chemotherapeutic drugs and several antioxidants including glutathione, melatonin, vitamins A, C,and E, and ellagic acid.

The good news is that the systematic review found no evidence that the effectiveness of chemotherapy was lessened by antioxidant supplication. Some trials reported better survival among the antioxidant groups.² Many studies reported decreased toxicities among patients receiving antioxidants and decreased neurotoxicity with glutathione supplements^{(3, 4)} was noted. The researchers caution the interpretation of these results, however, especially since most of the studies had very small sample sizes and were conducted in patients with advanced and or relapsed cancers. They emphasize the need for a large, well designed study of antioxidants used with chemotherapy.  I still feel this is a great step in the right direction. (From “Impact of antioxidant supplementation on chemotherapeutic efficacy: A systematic review of evidence from randomized controlled trials” by Keith I. Block, Amanda Koch, Mark N. Mead, Peter Tothy, Robert Newman, and Charlotte Gyllenhaal. Published online in Cancer Treatment Reviews, doi:10.1016/.ctrv.2007 .01.005)

References

¹ G.M. D’Andrea, Use of antioxidants during chemotherapy and radiotherapy should be avoided, CA Cancer J Clin 55(2005), p. 319-321

² P. Lissoni, Five years survival in metastatic non-small cell lung cancer patients treated with chemotherapy alone or chemotherapy and melatonin: a randomized trial, J Pineal Res 35(2003),p.12-15

³ S.Cascinu etal. Neuroprotective effect of reduced glutathione on oxaliplatin-based chemotherapy in advanced colorectal cancer: a randomized, double-blind, placebo-controlled trial, J Clin Oncol  20 (2002) p.3478-3483