Author: Catherine Gambaro
Published: Wednesday, October 24, 2012
A few weeks ago at the Academy of Nutrition and Dietetics Food and Nutrition Conference and Expo I had the opportunity to attend an educational session titled “Cancer Survivorship and Energy Balance: Going Beyond Obesity.” Knowing many people who have fought this frightening disease and being aware of the increasing number of cancer survivors, I thought this topic would be both interesting and beneficial. The presentation was conducted by Lee Jones, PhD, a specialist in exercise oncology from the Duke cancer institute, and Suzanne Dixon, MPH, MS, RD, an epidemiologist and registered dietitian known for her work with chronic disease prevention. Both presenters participated in research involving cancer survivors, and brought forth interesting information.
Many studies the speakers participated in and that other researchers conducted were presented in this session. It is important to know that most of this research involved breast and prostate cancer survivors and outcomes may or may not be generalized to the cancer population as a whole.
During and after cancer treatment increases in body weight and decreases in cardiovascular fitness are commonly seen. The most common cause of death in breast and prostate cancer survivors is cardiovascular disease. Research showed that the aerobic capacity of cancer survivors after treatment was 30% lower than that of age matched sedentary individuals without a history of cancer. This indicates that it is more than just weight gain and aging leading to this decline. The Multiple Hit Hypothesis was one explanation of this outcome. This states that there is damage to all systems as a result of the drugs and treatments for cancer, which impacts cardiovascular capacity. Supporting this hypothesis was a study showing an aerobic decrease of 9% after 12 weeks of chemotherapy when typically there is a 10% decline each decade as people age! In an effort to reduce this decline, studies have looked at the effect of aerobic training in conjunction with treatments to see if this would provide a protective effect. Results were not only protective, but showed improvements in cardiovascular fitness level and quality of life of participants.
Exercise studies in mice with tumors looked at tumor growth and metastasis, and cancer recurrence. Cancer cells grew slower and were less metastatic in the exercised mice and there was a 30% decrease in cancer recurrence in this population. Although this has not been studied in humans, these outcomes give support to exercise as an intricate part of cancer treatment. The suspected mechanism of these outcomes was increased blood flow to the tumors. Low blood flow to tumors makes them harder to treat, by increasing blood flow via exercise more medicine and immune cells can reach the tumor site.
Many times cancer patients are encouraged to eat anything that sounds good to them. This is done to keep patients strong and prevent weight loss during treatment. According to Ms. Dixon, this recommendation should be used with caution. Weight change during treatment cannot be ignored in this population and must be address whether a gain or loss. Significant change in either direction can affect treatment outcomes and post-treatment health. Weight gain is very common among breast and prostate cancer survivors. Possible reasons for this include eating habits during treatment carry over, associations between thinness and being sick, and decreased physical activity. Encouraging a balanced, healthy diet throughout cancer treatment can be beneficial on post treatment outcomes. A study looking at the effects of diet and exercise on obese and non-obese cancer survivors found that a diet including greater than 5 servings of fruits and vegetables per day with high physical activity resulted in decreased all cause mortality in both groups emphasizing the importance of post treatment lifestyle. It was also suggested that cancer survivors may have low interoception, ability of an individual to sense their body’s physiological condition (hunger, temperature, heart rate…). Using meditation and other exercises to increase this awareness may also result in better weight control in this population.
As dietitians we are always trying to produce the best outcomes for our clients and I thought this was a good example of how we can better address the needs of the growing population of cancer survivors. Exercise recommendations for this population have been published by the National Comprehensive Cancer Network and there is a Cancer Exercise Trainer Certification is available through the American College of Sports Medicine. Current nutrition recommendations for cancer can be found in the Academy of Nutrition and Dietetics Evidence Analysis Library.
Are exercise sessions and heart healthy diet counseling the next addition to some cancer treatments? As research continues it will be interesting to watch for shifts in traditional cancer treatment and the development of new opportunities for dietitians.