Washington, June 8 : A large number of women with breast cancer go for antioxidant supplements while undergoing cancer treatment, despite the possible side-effects of the practice remain unknown, according to a study.

The study called for additional research to determine the effects of antioxidant supplementation on the health and survival of breast cancer patients.

Antioxidant supplements include vitamin C, vitamin E, beta-carotene, and selenium, which are found in individual supplements as well as in many multivitamins.

Many breast cancer patients believe that antioxidant supplements will protect them from the side effects of breast cancer treatment, help prevent breast cancer recurrence, and improve their overall health.

But the actual effects of taking antioxidants during cancer treatment are poorly understood and the findings to date are mixed.

In fact, many physicians think that antioxidants may interfere with radiation and some types of chemotherapy, which often attacks tumour cells by generating reactive oxygen species (ROS)-very small molecules that play a role in cell development.

Led by Dr. Heather Greenlee, the research team investigated the prevalence of antioxidant use in women with breast cancer who participated in the population-based Long Island Breast Cancer Study Project (LIBCSP), which included more than 1,500 breast cancer patients

Greenlee''s study is based on the 764 patients who completed a follow-up interview and provided information on antioxidant supplement use.

Among the 764 patients studied, 663 women (86.8 percent) reported receiving chemotherapy, radiation, or hormone therapy for breast cancer.

Out of these 663 women, six in ten (60.5 percent) reported using antioxidants during breast cancer treatment, which included chemotherapy, radiation, and tamoxifen (anti-estrogen) therapy.

Almost seven in ten antioxidant users (69.3 percent) used high doses, defined as higher than the dose contained in a Centrum multivitamin.

The authors said: "Given the common use of antioxidant supplements during breast cancer treatment, often at high doses and in conjunction with other complementary therapies, future research should address the effects of antioxidant supplementation on breast cancer outcomes," including whether antioxidants affect treatment toxicities, treatment efficacy, cancer recurrence, and survival.

The study appears in an upcoming issue of CANCER, a peer-reviewed journal of the American Cancer Society. (ANI)