Journal of the National Cancer Institute Advance Access originally published online on October 28, 2008
JNCI Journal of the National Cancer Institute 2008 100(21):1559-1560; doi:10.1093/jnci/djn348
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© The Author 2008. Published by Oxford University Press.
CORRESPONDENCE |
Response: Re: Should Supplemental Antioxidant Administration Be Avoided During Chemotherapy and Radiation Therapy?
Affiliations of authors: Uniformed Services University of the Health Sciences, Bethesda, MD (BDL); Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, IN (BDL); Radiation Oncology Division and Breast Health Center, Naval Medical Center San Diego, San Diego, CA (BDL); Friedman School of Nutrition Science and Policy, Antioxidants Research Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA (JBB); Oncology and Medicine, McMaster University, Hamilton, ON, Canada (SMS)
Correspondence to: Brian D. Lawenda, MD, MC, USN, Radiation Oncology Division and Breast Health Center, Naval Medical Center San Diego, San Diego, CA (e-mail: brian.lawenda{at}med.navy.mil).
Largely on the basis of the same literature we systematically reviewed (1), Simone and Simone II (2,3) concluded that antioxidant supplementation does not interfere with chemotherapy or radiation therapy; indeed, they state (2) that as an adjunctive treatment, "antioxidant and other nutrient food supplements are safe and can enhance cancer patient care." Despite an appealing theoretical basis for the value of these nutrients in treating cancer patients, we feel that this position cannot be supported because there are few available studies of adequate design or statistical power to allow the determination of whether supplemental antioxidants protect tumors from chemotherapy or radiation therapy. Rather than simply noting the "thousands of patients" examined in these studies as Simone and Simone II have done, we focused instead on the quality and rigor of the studies in testing the hypothesis that high-dose antioxidant treatment is safe (1). As detailed in our commentary (1), the largest (n = 540) placebo-controlled clinical trial that has been reported demonstrated decreased local tumor control and survival in the patients who were randomly assigned to the concurrent radiation therapy and high-dose supplemental antioxidant group compared with those assigned to the radiation therapy and placebo group (4,5).
Simone and Simone II critique our commentary as incorrectly noting the number of trials cited in their review (2,3). In fact, although they listed 50 trials in their table (2), they also discussed two additional reports (references 11 and 40) elsewhere in the article (2). They also suggested that we revealed a bias by not mentioning the survival benefit of concurrent melatonin and chemotherapy in a study by Lissoni et al. (6). However, we discussed this potential benefit in the context of a larger trial conducted by the same authors (7). We also stated "these intriguing results should now be independently confirmed in larger trials" (1).
We feel strongly that in evidence-based medicine, data on safety obtained from randomized clinical trials are not "virtually equivalent" to results derived from observational studies. For example, associations found in observational data can never fully account for confounding factors in the comparison groups. On the basis of the indication of detrimental outcomes from a limited number of high-quality studies, we have assumed a conservative position, that is, that it is our ethical responsibility to inform our patients of the potential harm from high-dose antioxidant supplements when they undergo chemotherapy and/or radiation therapy.
NOTES
The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, Department of Agriculture or the United States Government.
REFERENCES
1. Lawenda BD, Kelly KM, Ladas EJ, Sagar SM, Vickers A, Blumberg JB. Should supplemental antioxidant administration be avoided during chemotherapy and radiation therapy? [see comment]. J Natl Cancer Inst (2008) 100(11):773–783.
2. Simone CB II, Simone NL, Simone V, Simone CB. Antioxidants and other nutrients do not interfere with chemotherapy or radiation therapy and can increase kill and increase survival, part 2. Altern Ther Health Med (2007) 13(2):40–46.[Web of Science][Medline]
3. Simone CB II, Simone NL, Simone V, Simone CB. Antioxidants and other nutrients do not interfere with chemotherapy or radiation therapy and can increase kill and increase survival, part 1. Altern Ther Health Med (2007) 13(1):22–28.[Web of Science][Medline]
4. Bairati I, Meyer F, Gelinas M, et al. A randomized trial of antioxidant vitamins to prevent second primary cancers in head and neck cancer patients [see comment]. J Natl Cancer Inst (2005) 97(7):481–488.
5. Bairati I, Meyer F, Jobin E, et al. Antioxidant vitamins supplementation and mortality: a randomized trial in head and neck cancer patients. Int J Cancer (2006) 119(9):2221–2224.[CrossRef][Web of Science][Medline]
6. Lissoni P, Chilelli M, Villa S, Cerizza L, Tancini G. 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. (2003) 35(1):12–15.[CrossRef][Web of Science][Medline]
7. Lissoni P, Barni S, Mandala M, et al. Decreased toxicity and increased efficacy of cancer chemotherapy using the pineal hormone melatonin in metastatic solid tumour patients with poor clinical status. Eur J Cancer (1999) 35(12):1688–1692.[CrossRef][Web of Science][Medline]
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