Helping Cancer Survivors Make Informed Choices About Diet and Exercise: Recommendations From the ACS

About 68% of Americans who receive a diagnosis of cancer live longer than 5 years.¹ Many of these cancer survivors seek advice about food, physical activity, dietary supplements, and complementary nutritional therapies. Recently, the American Cancer Society (ACS) issued a guide that provides clinicians with information that can help these patients make informed choices.² Highlights of the report follow.

TREATMENT AND RECOVERY

Nutrition. Prevention of unintentional weight loss and maintenance of normal energy levels are crucial, especially for patients who are undernourished. Anticipate potential nutritional difficulties, and build the dietary plan into the overall treatment strategy. For patients who experience anorexia, more frequent, smaller meals—rather than 3 large meals a day—may help increase intake. Commercially available or homemade nutrient-rich drinks may be helpful for patients who are unable to meet their nutritional needs through regular meals. For those who are at high risk of malnutrition, other means of nutritional support may be needed, such as pharmacotherapy using appetite stimulants, enteral nutrition via tube feeding, or intravenous parenteral nutrition.

Vitamin and mineral supplements. No consensus exists about the benefits and risks of supplement use during cancer therapy. The most prudent course is to advise patients who are receiving chemotherapy or radiotherapy to avoid exceeding the upper limits of the Dietary Reference Intakes for antioxidant vitamins such as C and E.³ General guidelines for the use of supplements are listed in Table 1.

Physical activity. Currently, there is no clear evidence regarding the effect of exercise on cancer treatment. Patients with a current exercise program should continue their activities as much as possible. Sedentary patients should start a new program with stretching activities and short walks. Advise patients who are receiving chemotherapy or radiotherapy to begin exercise at a lower intensity and build the activity level slowly. In patients for whom bed rest has been prescribed, physical therapy can help maintain strength and range of motion and may combat fatigue and depression.

AFTER RECOVERY

Nutrition. In most cases, evidence connecting specific food choices and exercise to cancer recurrence or survival is lacking or uncertain. However, following the ACS guidelines for healthy food choices may help reduce the risk of the occurrence of second cancers (Table 2).

Physical activity. Increased physical activity may forestall certain cancers, cardiovascular disease, diabetes, and osteoporosis.^4-7 It is probable that the relationship between increased physical activity and primary prevention of some cancers, cardiovascular disease, and diabetes also holds true for cancer survivors.

ADVANCED CANCER

Nutrition. Many patients with advanced cancer must modify their diet to meet new nutritional requirements and to accommodate such symptoms as pain, constipation, and anorexia. Consider nutrient-rich drinks in patients who cannot meet their nutritional needs with solid food. Use parenteral nutrition and tube feeding on an individualized basis and with a clear understanding of the risks.

Physical activity. Even modest physical activity may help relieve constipation, increase appetite, and counteract fatigue. However, the evidence is too limited to support general recommendations for exercise in this setting.

SPECIFIC CANCERS

Breast cancer. Among patients with breast cancer, increased adiposity is a significant risk factor for recurrent breast cancer and decreased survival.^8,9 Because weight gain after diagnosis is common,^8,10 encourage patients to maintain a healthy weight.⁴

Exercise—especially weight training—may help prevent or reverse weight gain.^11-13 A weight loss of 1 to 2 lb per week that does not interfere with treatment should be monitored closely and approved by an oncologist.^14,15 Even if the ideal weight cannot be achieved, a 5% to 10% loss in body weight over 6 to
12 months reduces elevated plasma lipids and high fasting insulin levels. Encourage moderate activity levels during and after treatment to maintain lean muscle mass, avoid excess body fat, and enhance quality of life.

While alcohol consumption is associated with a modest risk of primary breast cancer,⁸ moderate alcohol consumption (1 to 2 drinks a day) lowers the risk of cardiovascular disease. Data linking alcohol and risk of recurrence and survival are limited.⁸

Data that support an association between dietary fat and risk of breast cancer recurrence are inconsistent,^16,17 although limiting intake of saturated fat is important, because breast cancer survivors are at increased risk for cardiovascular disease.^7,18 Evidence of a link between increased fruit and vegetable intake and lowered risk is conflicting.^19,20 In moderate amounts, soy appears to be neither beneficial nor harmful; however, more than 3 servings a day may have an estrogenic effect,²¹ which increases the risk of breast cancer progression.²² Advise breast cancer survivors to consume a diet high in vegetables and fruits, low in saturated fat, and moderate in soy products.

Colorectal cancer. The risk of colorectal cancer is increased by diets high in red meat and saturated fats and low in fruits and vegetables, sedentary lifestyle, obesity, and possibly excess alcohol consumption.²³ However, it is currently unknown whether these factors affect the prognosis for colorectal cancer survivors. The risk of recurrence of colorectal cancer is increased slightly in smokers and in those who have 1 alcoholic drink per day, but it is significantly increased in smokers who also consume more than 1 alcoholic drink per day.²⁴

Currently, no evidence shows that antioxidant vitamins, fiber supplements, or modest increases in fruit and vegetable intake prevent new polyp growth during a 3- to 4-year period.²⁵ Calcium supplements have been shown to provide a modest benefit in preventing polyp growth.²⁶ Emerging evidence suggests that vitamin D status may influence outcomes in colorectal cancer survivors as well.²⁷ Refer to a registered dietitian patients with a history of bowel problems or those undergoing surgery that affects normal nutrient absorption.

Exercise is likely beneficial in reducing the risk of second primary colorectal cancer and in increasing the overall survival. Advise patients to maintain a healthy weight, eat a well-balanced diet consistent with guidelines for cancer and heart disease prevention, and participate in regular physical activity.

Lung cancer. While lung cancer is largely associated with cigarette smoking, there is also a link with diets low in vegetables and fruits.²⁸ During treatment and the immediate recovery period, a diet of smaller, more frequent meals of calorie-concentrated, easy-to-swallow foods is helpful. Additional nutritional support is appropriate for patients with unintentional weight loss.²⁹

Prostate cancer. A decreased intake of saturated fat and an increased intake of fruits and vegetables can lower the risk of cardiovascular disease, a leading cause of death in prostate cancer survivors.^22,30 Small studies of flaxseed oil and soy showed that they inhibited prostate cancer growth, but their effects on prognosis are unknown.³⁰ One study showed an association between vitamin E and a reduced risk of primary prostate cancer and aggressive disease, but there was no effect on survival.^31,32 A small trial found that selenium supplements reduced prostate cancer incidence.^33,34; however, a more recent trial showed no protective effect.³⁵

Men with high calcium intakes, either from diet or supplements, might be at heightened risk for prostate cancer and aggressive disease.³⁶ The role of calcium after diagnosis is currently unknown. Prostate cancer survivors undergoing androgen-suppressive therapy are at high risk for osteoporosis, but it is not known whether calcium or vitamin D would be beneficial in this setting.

In one study, mortality was higher among overweight prostate cancer survivors.³⁷ Weight control and increased physical activity may prevent other chronic diseases and improve overall survival.