Although the consequences of supplementing with antioxidants during cancer treatment remain unknown, many patients with breast cancer continue to use the supplements in an effort to maintain health and diminish the side effects of treatment, according to the results of a study published in Cancer.
Antioxidants found in many foods (including fruits, vegetables, grains, nuts, as well as some meats, poultry, and fish) are often praised for their health benefits, namely the slowing or preventing of damage to cells caused by unstable molecules known as free radicals. For cancer patients, however, use of antioxidants, such as vitamins A, C, and E; beta carotene; lycopene; and selenium, in supplemental form (as opposed to food sources) is controversial. High doses of antioxidants may reduce the ability of radiation or chemotherapy to kill tumor cells, potentially reducing the effectiveness of treatment.
Despite the controversy, many patients continue to supplement with antioxidants. Between 2002 and 2004 researchers with the Long Island Breast Cancer Study Project conducted a follow-up interview of 764 women with breast cancer who had participated in a case-control study between 1996 and 1997. Of the 764 women, 663 reported receiving adjuvant treatment for breast cancer.
Approximately 60% (401) of the women who underwent adjuvant treatment reported using antioxidant supplements during the treatment. Furthermore, of these 401 women, 278 (69.3%) reported using high doses of antioxidants. More specifically:
-120/310 women (38.7%) used antioxidants during chemotherapy.
-196/464 women (42.4%) used antioxidants during radiation therapy.
-286/462 women (61.9%) used antioxidants during tamoxifen (Nolvadex®) therapy.
The researchers concluded that the use of antioxidant supplements during breast cancer treatment is common and future studies should evaluate the effects of antioxidants on breast cancer outcomes. In the meantime women who are considering using dietary supplements should be sure to discuss their supplement use with their physician. It’s important that the physician be aware of anything the patient is using that could potentially interfere with treatment.
 Greenlee H, Gammon MD, Abrahamson PE, et al. Prevalence and predictors of antioxidant supplement use during breast cancer treatment. Cancer. 2009; 114: 3271-3282.