Physical activity is therapeutic for a wide range of health conditions, including breast cancer -- and not merely because exercise improves the way people look and feel. Breast cancer patients who follow regular programs of even moderate exercise may dramatically decrease the chances of disease recurrence by boosting the efficiency with which their bodies metabolize insulin.
Insulin and Insulin Resistance
Insulin, a hormone made by the pancreas, controls the level of glucose in the blood. Without it, the cells are unable to convert this sugar into energy. Insulin resistance, also known as metabolic syndrome, refers to a group of factors that affect the body's ability to use insulin effectively and increase the risk of heart disease, stroke and type 2 diabetes. When cells don't get enough glucose, the pancreas over-produces insulin and as levels of glucose and insulin rise --- so do levels of blood fats, affecting kidney function. Being overweight is a major risk factor for insulin resistance, especially when extra weight is concentrated around the midsection.
Findings of Studies
A Harvard Medical School study published in the May 25, 2005, "Journal of the American Medical Association" found breast cancer survivors who walked for three to five hours a week, or exercised more strenuously for shorter periods of time, had a 50 percent lower risk of disease recurrence, regardless of the size of the cancer at time of diagnosis. A Yale School of Medicine study published in the December 2010 "Journal of Clinical Oncology" followed the progress of 527 breast cancer patients for five years, finding an association between improved insulin sensitivity as a result of exercise and increased life expectancy.
Exercise and Risk Reduction
Obesity is a known risk factor for insulin resistance and research suggests that insulin resistance may be a risk factor for disease recurrence in breast cancer patients. Therefore, by helping to reduce body weight and direct fat distribution away from danger areas, the midsection and hips, exercise helps the cells metabolize insulin more efficiently. Jennifer Ligibel of the Dana-Farber Cancer Institute in Boston, one author of a 2007 study on the effects of a 16-week program of cardiovascular exercise and strength training on breast cancer prognosis, says, "Exercise has benefits all through treatment and afterward. It's an investment in a woman's health and hopefully will prove to lower her risk of dying from breast cancer."
Exercise Recommendations for Breast Cancer Patients
Yale School of Medicine endorses exercise for all breast cancer patients but advises women to consult their doctors before starting, especially if they are still undergoing active treatment. Women with no underlying health problems can usually follow any exercise program of their choice after treatment is finished. Start gradually by exercising five to 10 minutes a day and work up to 30 minutes. Walking, cycling, swimming and strength training are all beneficial, as are fitness clubs, many of which now have special programs for cancer survivors. Staying motivated is essential and according to Yale, some studies have found women who walk in their own neighborhoods stick with their exercise routines longest because no travel is required.
References
- Yale School of Public Health: Insulin Levels Found to Affect Breast Cancer Survival, Dec. 2010
- Harvard Health Publications: Harvard Medical School: Exercise Helps Breast Cancer Survivors Live Longer
- Dana-Farber Cancer Institute: Exercise Lowers Insulin in Breast Cancer Survivors, June 4, 2007
- Medicine Net: Definition of Insulin
- PubMed: Metabolic Syndrome (Insulin Resistance Syndrome)
