More on Lifestyle Choices
I have written before about the possible value of exercise on reduction of breast cancer recurrence risk. Here is a brief summary from ASCO re the likely benefit of lifestyle choices:
Lifestyle Modification May Benefit Patients with Cancer, Reduce Comorbidities
Diet, exercise, and the use of supplements are commonly regarded as healthy lifestyle choices if used correctly and in moderation. Despite this, diet and exercise often are not included in routine cancer care counseling, possibly because of the lack of definitive research analyzing the effects of such recommendations. The Education Session held yesterday, "Diet, Exercise, and Cancer: Does the Evidence Support Lifestyle Modification as Part of Cancer Treatment?," featured lectures on vitamin D, physical activity, weight management, and diet. Session Chair Pamela Jean Goodwin, MD, of Princess Margaret and Mount Sinai Medical Center at the University of Toronto, urged oncologists to review the strongly suggestive observational data and to continue to research these topics so more definitive answers can be found.
The Session focused on observational evidence that suggests a possible link between obesity, physical activity, diet, vitamin D intake, and possibly supplement use, as it relates to cancer risk and prognosis. A healthy lifestyle also has been found to have beneficial effects on comorbidities, such as cardiovascular disease, that often are associated with various types of cancer.
"There is a lot of observational evidence that suggests people who are physically active are less likely to develop a number of common cancers," said Jennifer Ligibel, MD, of the Dana-Farber Cancer Institute and Harvard Medical School, in an interview with
ASCO Daily News. "There is also evidence that breast and colorectal cancer survivors who are physically active after diagnosis appear to have a better prognosis as compared with sedentary individuals."
Dr. Ligibel also noted that a number of physical activity interventional trials have been performed involving patients with cancer. These studies have shown that most patients can safely engage in moderate-intensity exercise (e.g., walking), both during and after cancer treatment and that sedentary individuals who begin to exercise often experience improvements in quality of life and in energy levels. "If you can get people who are not exercising to start an exercise program, they often feel better, have more energy, and may experience fewer treatment-related side effects," she said.
Although research is needed to explore the effect of lifestyle change, dietary modification, and supplement use on cancer risk and prognosis, there are ways in which diet, in addition to exercise, may affect cancer, aswell as reduce the risk for comorbidities that are prevalent in the general population and especially among cancer survivors. Wendy Demark-Wahnefried, PhD, RD, of M. D. Anderson Cancer Center, reviewed currentdietary recommendations that emphasize plant-based, unrefined foods and low intakes of saturated fat, simple sugars, and red and processed meats. "The evidence that we have for this is really based more on the comorbidity that these patients tend to have and a need to promote weight control," she said in an interview with
ASCO Daily News. In her lecture, Dr. Demark-Wahnefried also noted the lack of evidence suggesting any benefit of the notion of extreme dieting. "More research needs to be done in these areas. Certain foods do have benefit or unique nutrient compositions that make them compelling, but we're just not at the point of being able to recommend one over another."
Dr. Goodwin also discussed vitamin D, and she began with a discussion of its basic physiology and molecular biology, as it is a relatively new area of interest within the field of oncology. She then provided an overview ofthe evidence, or lack thereof, linking vitamin D to positive outcomes for patients with cancer. If you look at the evidence linking vitamin D to cancer [prevention], it's not particularly strong. An exception is for colorectal cancer where there are a fair number of studies that suggest a link between low vitamin D levels and increased colorectal cancer risk," Dr. Goodwin said in an interview with
>ASCO Daily News>.
Similar to the advice of Dr. Demark-Wahnefried in regard to extreme dieting, Dr. Goodwin strongly urged against the use of "mega doses" of vitamin D. "There is a huge healthy range, and the available evidence suggests that general health is maximized when you're toward the lower end of that range," explained Dr. Goodwin. "It is also important to realize that vitamin D is not a substitute for all the other healthy behaviors that we're [discussing]."
Dr. Goodwin noted that there are little data from randomized controlled trials demonstrating that changing diet and exercise patterns after cancer diagnosis will lead to improvements in prognosis. A notable exception is the Women's Intervention Nutrition Study (WINS) that reported a reduced risk of recurrence for patients with breast cancer who were randomly assigned to diets that lowered fat intakes and that resulted in modest weight loss. She stressed the importance of using biologic rationale in combination with observational data to begin to emphasize the importance of diet and exercise to patients with cancer. "I think that this may come as a surprise to many oncologists that the observational data have really not translated into benefits in intervention studies," she said. "We need to be very careful when we draw from a single [study] or even from a group of observational studies into implying benefit."
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