Antioxidant Vitamins May Enhance Benefits of Radiation Therapy in Cancer While Protecting Healthy Tissues

BACKGROUND: The use of antioxidant supplements in cancer patients undergoing radiation therapy is a controversial issue in cancer treatment. Radiation therapy kills cancer cells by generating large numbers of destructive free radicals. Some oncologists believe that antioxidants may reduce the benefits of radiation therapy, while others believe that antioxidants may improve the efficacy of the radiation therapy, while protecting normal cells.

RESEARCH: A review of antioxidant supplement use in patients undergoing radiation therapy showed that high-doses of vitamins A, C, and E (particularly natural vitamin E succinate), and beta-carotene, may inhibit the growth of many different types of cancer cells in culture, without inhibiting the growth of normal cells. Low doses of antioxidants do not appear to have this anti-cancer effect.

RESULTS: In a pilot clinical trial, as well as in uncontrolled clinical experiences, physicians have found that high-dose antioxidant supplements before and after radiation therapy led to an improved quality of life without any adverse effects in patients undergoing radiation therapy or chemotherapy combined with radiation therapy. Some researchers suggest that the antioxidants should be taken at least 48 hours before radiation therapy begins to initiate the cancer-fighting properties of the vitamins.

IMPLICATIONS: This review suggests that the clinical use of high-dose antioxidant supplements, particularly vitamins A, C, E (succinate) and beta-carotene, may be beneficial as an adjunct treatment in cancer patients undergoing radiation therapy.

Prasad KN, Cole WC, Kumar B, et al, "Pros and cons of antioxidant use during radiation therapy," Cancer Treatment Reviews, 2002;28:79-91.

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