Naturopathic Doctor Studies Antioxidant Use in Breast Cancer Patients

Center for Cancer Training

Many cancer patients take over-the-counter antioxi­dant dietary supplements while undergoing radiation therapy or chemotherapy. The use of antioxidant sup­plements is controversial because doctors know little about the short-term or long-term effects. There is a concern that antioxidant supplements may counteract the effects of chemotherapy and radiation therapy, yet antioxidant supplements may also prevent side effects caused by cancer treatments.

“We do not have good data to inform clinical guide­lines either way,” explained Heather Greenlee, N.D., Ph.D., M.P.H, recipient of a five-year Mentored Pa­tient-Oriented Research Career Development Award* from NCI. Dr. Greenlee, an assistant professor in the epidemiology department at Columbia University’s Mailman School of Public Health, is using the NCI grant to help gather data to help resolve the contro­versy over antioxidant supplement use, in particular during adjuvant therapy for breast cancer. Adjuvant therapy is any treatment given after the primary treatment to reduce the risk that cancer will recur.

As part of this research, Dr. Greenlee will do pre­liminary clinical studies on the safety and potential benefits of one particular antioxidant, coenzyme Q10 (CoQ10), in women undergoing chemotherapy with doxorubicin, a drug used to treat many types of can­cer. “Doxorubicin can cause significant cardiac toxic­ity—that is, damage to the heart muscle,” noted Dr. Greenlee. “For some women with breast cancer, this resolves after treatment is over, but for other women there is permanent damage.”

CoQ10 has been shown in laboratory cell cultures and animal studies to prevent cardiac toxicity caused by doxorubicin, but a definitive study has never been done in breast cancer patients, Dr. Greenlee said. An estimated 45% to 80% of breast cancer patients take antioxidant supplements such as CoQ10, either for general health benefits or because they hope the supplements will help treat the cancer or keep it from recurring.

To address the question of the potential benefits of antioxidant supplements from a different angle, Dr. Greenlee will also use data from the Pathways Study, an ongoing observational epidemiology study being funded by NCI. The Pathways Study is gather­ing detailed information on diet, dietary supplement use, and physical activity from more than 4,000 women diagnosed with breast cancer within the Kaiser Permanente Northern California health sys­tem. “We will be able to use the Pathways Study data to see whether or not the use of antioxidants during radiation therapy or during chemotherapy impacts the breast cancer recurrence rate or survival rate,” Dr. Greenlee explained.

Dr. Greenlee is one of a handful of naturopathic doctors (N.D.) who are doing cancer research. Prior to going to a naturopathic medical school, “I’d been a research assistant at the Fred Hutchinson Cancer Research Center and I wanted to be able to identify things that women can do proactively to promote their health and prevent cancer,” she recalled. “I turned to naturopathic medicine to provide a model of health promotion and wellness, and that turned into me being interested in what cancer survivors can do beyond conventional treatment to improve their quality of life, to improve their recurrence rates, and overall improve their survival.”

After her naturopathic training, Dr. Greenlee pursued a Master of Public Health degree in epidemiology at the University of Washington and a Ph.D. degree in epidemiology at Columbia University. Once she completes the additional training, course work, and mentoring provided by the NCI career development award, “my goal is to lead a major research pro­gram on the effects of CAM therapies and lifestyle modifications after cancer diagnosis for reducing side effects, reducing recurrence rates, and improving survival—to identify what works and what doesn’t work,” she commented.