AACR 2009: Oncologists Should Recommend Exercise, But Not Supplements

Zosia Chustecka

April 23, 2009

April 23, 2009 (Denver, Colorado) — Oncologists should recommend exercise to cancer patients; there is accumulating evidence to show that it can improve both prognosis and quality of life, according to Melinda Irwin, PhD, MPH, associate professor of epidemiology and public health at the Yale School of Medicine, in New Haven, Connecticut.

However, the evidence for supplements, such as vitamins, minerals, and antioxidants, is insufficient to make any science-based recommendations on their use in cancer patients, according to Cornelia Ulrich, MS, PhD, from the Fred Hutchinson Cancer Center, University of Washington, in Seattle.

Both were speaking at a symposium on cancer survivorship here at the American Association for Cancer Research 100th Annual Meeting.

The best evidence for the benefits of exercise comes from studies of breast cancer patients, where it has been shown to reduce the risk for relapse and mortality — both from cancer and all causes, Dr. Irwin said. There is also some evidence of a similar benefit in prostate and colorectal cancer. "But I would strongly hypothesize that the benefits from exercise — particularly for improving quality of life — would extend to all cancers," she told Medscape Oncology.

In reviewing studies showing benefits from exercise, Dr. Irwin cited 1 that her own group published recently (J Clin Oncol. 2008:24;3958-3964). The Health, Eating, Activity and Lifestyle (HEAL) study of 933 breast cancer patients showed that moderate-intensity physical activity reduced the risk for death by 67% in women who remained active 2 years after diagnosis. This was both breast cancer mortality and deaths from other causes, mostly cardiovascular disease and diabetes, she added.

Other studies have suggested that exercise reduces the risk for breast cancer mortality by 40% to 55%, "which is as much as standard treatments," she said.

These studies have varied in their recommendations for exercise — some aimed for 90 minutes a week, others for 2 to 3 hours a week, but the HEAL study showed a benefit from any amount of exercise, she said. In some of the studies, exercise started at diagnosis and continued throughout and after the treatment.

"Any amount of exercise is better than none," Dr. Irwin said.

"Oncologists are uniquely placed to recommend exercise, and they have the perfect opportunity to intervene as treatment is ending, because patients are then eager to learn what else they can do to help themselves," she explained to Medscape Oncology.

"Of course, oncologists do not have the time to discuss exercise regimens in detail," Dr. Irwin acknowledged, but the fact that the recommendation is made by them, as cancer specialists, is "very valuable."

"Our study showed that oncologist recommendation is a strong predictor of uptake," she said, "but only half the patients in the study said that their oncologist had mentioned exercise."

A new development may make it possible soon for oncologists in the United States to refer their cancer patients to physical-fitness professionals that are specifically trained for this work. The American Cancer Society and the American College of Sports Medicine launched a Certified Cancer Exercise Training course in January 2009.

"This would make it much easier for oncologists," Dr. Irwin noted. "They could recommend exercise, and then refer the patient to a trained professional."

Insufficient Evidence on Supplements

In contrast to exercise, the use of supplements by cancer patients cannot be recommended at present; there is insufficient evidence to make science-based recommendations, Dr. Ulrich told the audience.

Some studies have suggested a benefit, but there have also been some that suggested adverse effects, she said. For example, 1 study suggested that antioxidants interfere with radiation therapy in patients with head and neck cancer, whereas another showed that the popular herbal remedy St. John's wort significantly reduced the efficacy of irinotecan by interfering with its metabolism.

Despite the lack of evidence, supplements are used by the majority of cancer patients, Dr. Ulrich said. A recent review found that 64% to 81% of all adult cancer patients in the Untied States take supplements, and 14% to 32% of them started taking them after diagnosis. When asked why, patients said they took supplements "in order to feel better, to enhance their chance of a cure, to retain a sense of control, and to ensure adequate nutrition."

Another study found that 31% to 68% of cancer patients and long-term survivors take supplements but don't tell their doctors, she said.

Dr. Irwin and Dr. Ulrich have disclosed no relevant financial relationships.

American Association for Cancer Research (AACR) 100th Annual Meeting. Symposium held April 21, 2009.


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