Fitness level may be key to surviving breast cancer

Fitness is key to health, as we are all told regularly, and watching your weight and exercising regularly can cut your risk of developing cancer. According to a study published in the Journal of Clinical Oncology, women with better cardiovascular fitness also had a better chance of surviving breast cancer.

Most cancer chemotherapy regimens are toxic by nature. The drugs that are designed to kill cancer cells also damage healthy cells, and this includes cells in the lungs, heart, blood and skeletal muscle, affecting the function of the heart and lungs. Cancer patients can also have little energy for exercise and gain weight, which also affects the cardiopulmonary system.

To check this, the team from Duke University checked the fitness levels of 248 women at different stages of breast cancer. The combination of tissue damage and lack of exercise meant that women with breast cancer had peak oxygen consumption (VO2peak), a key measure of cardiopulmonary fitness, over a quarter lower than healthy women, and this effect was regardless of treatment status and lasted for years after treatment. Fitness had an impact on survival, too. The women with the best levels of fitness survived for a median of 36 months, whereas those with low levels of fitness only survived for a median of 16 months, meaning that this could be used as a biomarker to predict their chance of survival with advanced breast cancer.

"We know that exercise tolerance tests, which measure cardiopulmonary function, are among some of the most important indicators of health and longevity in people who do not have cancer; however, relatively little research has been done assessing the clinical importance of these tests in patients with cancer," said Lee Jones, Ph.D., associate professor at Duke and lead author of the study. "Our work provides initial insights into the effects a cancer diagnosis and subsequent therapy may have on how the heart, lungs and rest of the body work together during exercise."

It's not yet clear whether this is cause or effect, and whether improving fitness would improve survival, but if it does, it could be a low-cost intervention to improve outcomes and the researchers are looking at the effects of exercise training on women with breast cancer, plus patients with other cancers.

In another story from Cancer Epidemiology, Biomarkers & Prevention, leg length and sitting height are also biomarkers for risk of breast cancer, though not markers that can be as easily changed as exercise levels. Leg length is linked with increased risk of post-menopausal estrogen receptor-positive tumors and sitting height with a decreased risk of premenopausal estrogen-receptor-negative tumors.

- read the press release about fitness
- see the abstract about fitness
- check out the abstract about height