Persons across the spectrum of cancer survival should strive to achieve and maintain a healthy weight.17 Some cancer survivors can be malnourished and underweight at diagnosis or as a result of aggressive treatment. For these persons, further loss of weight can impair their quality of life, interfere with completion of treatment, delay healing, and increase complications. In survivors with these difficulties, dietary intake and all factors affecting energy expenditure should be carefully assessed. For those at risk for unintentional weight loss, multifaceted interventions should focus on increasing food intake and reducing total energy expenditure to achieve a positive energy balance and thereby increase weight.26 Physical activity may be useful to the underweight survivor when tailored to provide stress reduction and to increase strength, but high levels of physical activity make weight gain more difficult.14
Obesity is a risk factor for some of the most common cancers in the United States, such as postmenopausal breast cancer and colorectal cancer.21 For this reason and because obesity is increasingly common in the US population,31 many cancer survivors are overweight or obese at the time of diagnosis. Increasing evidence indicates that being overweight increases the risk for recurrence of many cancers,32–35 and a recent study links obesity with an increased risk for dying of cancer.36 In women with breast cancer, this problem is compounded because of weight gain associated with adjuvant therapy.37,38 For cancer survivors who are overweight or obese, modest weight loss (ie, a maximum of 2 pounds per week39,40) can be encouraged during treatment, as long as the treating oncologists approve, weight loss is monitored closely, and weight loss does not interfere with treatment. Safe weight loss should be achieved through a healthful, well-balanced diet (see Balancing Fat, Protein, and Carbohydrate Intake) and physical activity tailored to the specific needs of the person being treated.
After cancer treatment, weight gain or loss should be managed with a combination of dietary and physical activity strategies. For some who need to gain weight, this means increasing caloric intake (food intake) to exceed energy expended, and for others who need to lose weight, this means increasing energy output (physical activity) to exceed caloric intake. Moderate physical activity during and after treatment will help survivors maintain lean muscle mass while reducing body fat. For those who need to lose weight, even if ideal weight reduction is not achieved, it is likely that any weight loss achieved by physical activity and healthful eating is beneficial.
Balancing Fat, Protein, and Carbohydrate Intake
Fat, protein, and carbohydrate all contribute calories to the diet, and each of these dietary constituents is available from a wide variety of foods. Making informed choices about foods that provide these macronutrients can ensure variety and nutrient adequacy. A common misconception is that all fats, proteins, or carbohydrates are similar in their health effects. It is now clear that the type of fat, protein, or carbohydrate and the food source can make a difference in long-term health. The choice of such foods is probably more important than the total amount of fat, carbohydrate, or protein in the diet. Many cancer survivors are at high risk for other chronic diseases, such as heart disease. Therefore, the recommended amounts of fats, proteins, and carbohydrates for cardiovascular health are appropriate for cancer survivors.16–20
Although much historical interest has been focused on linking dietary fat with cancer risk, especially breast cancer and colorectal cancer, the current evidence indicates it is unlikely that a high level of total fat in the diet is an important cause of cancer.41–43 Total fat intake has not been linked to the risk for recurrence or survival in most studies reported to date.32–34,45 However, two important randomized clinical trials are testing the effect of a low-fat dietary pattern on risk for recurrence and survival in women with breast cancer (the Women's Intervention and Nutrition Study [WINS] and the Women's Healthy Eating and Living Study [WHEL]).46,47
There are many types of dietary fat. Some fats, such as monounsaturated and omega-3 fatty acids, are associated with reduced risk for heart disease and possibly cancer, whereas others, such as saturated fats, are associated with increased risks.18–20 Some studies have suggested that omega-3 fatty acids may have specific benefits for cancer survivors. These findings are not certain, and more research is needed.48 Eating foods rich in omega-3 fatty acids (eg, fish and walnuts) is encouraged because this is associated with a lower risk for cardiovascular diseases and a lower overall mortality rate.17,19, 20
Adequate protein intake is essential during all stages of cancer treatment, recovery, and long-term survival. The best choices to meet protein needs are foods low in saturated fat (eg, fish, lean poultry, eggs, low-fat meat, nonfat and low-fat dairy products, nuts, seeds, and legumes). An intake of 10% of calories from protein will generally meet the protein needs of adult cancer survivors; however, most elderly need a higher proportion of calories from protein, given reduced energy intake. Importantly, however, persons with renal dysfunction may need to restrict their protein intake.
Healthful carbohydrate choices are foods that are rich in essential nutrients, phytochemicals, and fiber, such as whole grains, vegetables, legumes, and fruit. These foods should constitute the majority of carbohydrate-containing foods in the diet. Because nutrient-poor, low-fiber, carbohydrate-rich foods (highly refined foods such as white bread and rice or foods with added sugar) simply add calories to the diet or replace more healthful foods, and thereby reduce the overall diet quality, these foods should be only a small source of carbohydrate in the diet. Foods high in refined sugars or carbohydrates may also exacerbate insulin resistance. Although it is unknown whether insulin resistance is important in cancer survival, there is growing interest in determining whether these foods may increase the risk for certain cancers such as breast, colorectal, or pancreatic, and insulin resistance seems to play an important role in increasing obesity and the risk for diabetes and cardiovascular disease.19,20
Balancing fat, protein, and carbohydrate is challenging for the cancer survivor who eats a vegetarian diet. Vegetarian diets differ with respect to inclusion of dairy foods, fish, and/or eggs, but avoiding red meat is a universal feature. Although plant foods are sources of incomplete proteins that lack or are low in one or more essential amino acids, vegetarian diets that include fish and dairy foods typically contain the same quantity and quality of protein provided by nonvegetarian diets. A vegan diet excludes all animal foods and animal products. Adults eating vegan diets can meet protein needs if they consume nuts, seeds, legumes, and cereal-grain products in sufficient quantities.
Cancer survivors who eat a vegetarian diet need to use care to prevent nutrient inadequacy. In general, the risk for nutrient deficiencies and inadequate energy intake is greater with greater food restrictions. Regular use of a multiple vitamin/mineral supplement containing 100% of Daily Values may be indicated to prevent nutrient deficiencies, especially if the amount and types of foods being consumed by the individual eating a vegetarian diet are very limited. Vegan diets should be supplemented with vitamin B12, iron, and zinc, or include foods that are fortified with these micronutrients.49 During cancer treatment, eating a vegetarian diet may necessitate guidance from a dietitian to minimize adverse effects, such as diarrhea during radiation therapy.
Vegetarian diets include many health-promoting features, because they tend to be low in saturated fat and high in fiber, vitamins, and phytochemicals, and a vegetarian diet can be consistent with the ACS nutrition guidelines for the prevention of cancer. However, no direct evidence has determined whether consuming a vegetarian diet has any additional benefit for the prevention of cancer recurrence.
Vegetables and Fruits
Higher intake of vegetables and fruits may be associated with a lower incidence of colorectal and lung cancers as well as oral, esophageal, and stomach cancers.18 A diet including many vegetables and fruits might also be beneficial for reducing the risk for cancer recurrence or increasing survival, but few studies exist of this relationship in cancer survivors. The benefits of eating a variety of vegetables and fruits probably exceed the health-promoting effects of any individual component, because it is likely that the various vitamins, minerals, and other phytochemicals in these whole foods act in synergy to reduce cancer risk.
It is reasonable for cancer survivors to adopt the general dietary recommendations issued by the ACS and many other organizations to eat at least five servings of vegetables and fruits each day. Vegetables should be especially encouraged because they are more nutrient dense than most fruits. Micronutrient- and phytochemical-rich vegetables in a variety of deep colors and flavors should be selected. Selection of a variety of colors is a simple way to ensure that the diet includes a variety of different phytochemicals. Frozen and canned vegetables and fruits may be more readily available and less expensive than fresh vegetables and fruits, and they are nutritionally comparable to fresh. Because chemotherapy can impair the immune response, raw vegetables may increase the risk for infection in some patients during treatment as a result of pathogens on these foods.50 Steaming or otherwise cooking vegetables increases the absorption of many nutrients and other phytochemicals, improves tolerance, and decreases the risk for infection. A serving size of vegetables or fruits is defined as one medium piece of fruit; one-half cup of chopped, cooked or canned fruit; one-quarter cup of dried fruit; 6 ounces of 100% fruit or vegetable juice; one cup of raw leafy vegetables; or one-half cup of cooked or raw vegetables.
Substantial evidence indicates that alcohol intake has both positive and negative health effects.51–53 For this reason, it is important for the health care provider to tailor advice on alcohol consumption to the individual cancer survivor. The cancer type and stage of disease, treatment, risk factors for recurrence or new primary cancers, and comorbid conditions should be considered in making recommendations. For example, alcohol, even in the small amounts found in mouthwashes, can be irritating to survivors with oral mucositis and can exacerbate that condition. Therefore, it is reasonable to recommend that alcohol intake should be avoided or limited among survivors with mucositis and among those beginning head and neck radiotherapy or chemotherapeutic regimens that put them at risk for mucositis.
Many studies have found a link between alcohol intake and risk for some primary cancers, including cancers of the mouth, larynx, esophagus, liver, breast, and possibly colon.51,52,54 In persons who have already received a diagnosis of cancer, alcohol intake could also affect the risk for new primary cancers of these sites. Alcohol intake can increase the circulating levels of estrogens, which theoretically could increase the risk for recurrence of breast cancer, but in studies conducted to date this increased risk has not been observed.34 Therefore, the degree of risk present should be considered in recommendations regarding individual alcohol consumption.
In the general population, consistent evidence links modest alcohol intake of one to two drinks per day with a lower risk for cardiovascular disease.53 One drink is defined as 5 ounces of wine, 12 ounces of beer, or 1.5 ounces of hard liquor. Because some cancer survivors are at risk for cardiovascular disease and for cancer recurrence and new primary cancers, the potential benefits and risks of alcohol use must be weighed carefully on an individual basis.
Dietary supplements include vitamins, minerals, herbs, botanicals, amino acids, and glandular products. The use of dietary supplements is reported in 25% to 80% of cancer survivors.55,56 One of the rationales for dietary supplement use stems from observations of lower cancer risk among those who eat diets rich in vegetables and fruits. There is little evidence, however, that dietary supplements can reproduce the benefit of a nutrient-rich diet. Few studies have examined the efficacy of dietary supplements as an alternative or complementary cancer treatment.
During and after cancer treatment, there is a probable benefit of taking a standard multiple vitamin and mineral supplement that contains approximately 100% of the Daily Value because, during these times, it may be difficult to eat a diet with adequate amounts of these micronutrients.57,58 In contrast, the use of very large doses of vitamins, minerals, and other dietary supplements can cause physical harm.59,60 The Dietary Reference Intakes provide recommendations of amounts of most vitamins and minerals needed for optimal health as well as the established Upper Tolerable Limits for most healthy persons.6 Identification of upper tolerable limits and toxic effects is important because, for some, the practice of dietary supplementation has moved beyond the goal of health promotion and disease prevention to include speculation that dietary supplements may be instrumental in cancer prevention and treatment. There is reason for caution in taking high-dose supplements. Although many observational epidemiologic studies found that dietary beta-carotene was associated with lower risk for lung cancer,61 two clinical trials showed that high-dose beta-carotene supplements actually increase (not decrease) the rate of occurrence of lung cancer.59,60 In addition, another recent trial suggests that beta-carotene supplements may increase colorectal adenoma recurrence in persons who smoke cigarettes, consume alcohol, or both.62 High doses of beta-carotene taken as a supplement do not appear to have the same effect as beta-carotene found in food.
In conclusion, although there is tremendous enthusiasm for expanding current cancer prevention and treatment options to include dietary supplements, and although supplement use is very common among cancer survivors, studies of the effect of nutritional supplements on cancer recurrence and survival are few. It is still prudent to encourage cancer survivors to obtain the potentially beneficial compounds from food. A daily multivitamin supplement in amounts equivalent to 100% of the Daily Value is a good choice for anyone who, for whatever reasons, cannot eat a healthful diet,57,58 but the use of vitamin and mineral supplements in higher doses should be assessed and discussed on an individual basis.
Physical Activity Issues for Cancer Survivors
Physical activity may have benefits throughout the spectrum of living with cancer, but cancer survivors are often at increased risk for becoming too sedentary for several reasons. First, survivors tend to decrease their physical activity levels after the diagnosis of cancer, and most continue lower levels of activity through treatment and beyond, rarely returning to their prediagnostic levels of activity.63–65 Second, some therapies may reduce the capacity to exercise because of adverse effects on cardiopulmonary, neurologic, and muscular systems. Third, being sedentary is a risk factor for the incidence of several of the most common types of cancer, such as breast cancer and colorectal cancer, and therefore persons with these cancers will tend to continue to be sedentary. Thus, reduced levels of fitness, stamina, and strength and the stresses of cancer diagnosis, treatment, and recovery challenge cancer survivors who want to increase their physical activity levels. For these reasons, exercise that is of low or moderate intensity for a healthy person may be of high intensity for some cancer survivors.
Physical activity capabilities and effects will differ among cancer survivors depending on their diagnosis, treatment modalities, and the spectrum of cancer survival.66 Many cancer survivors are at increased risk for comorbid conditions that can be reduced through increased physical activity.22 The effects of physical activity on cardiovascular disease and diabetes have not been studied in the population of cancer survivors, but there is no reason to believe that such outcomes would differ from those observed in the general population. Similarly, resistance exercise has been reported to improve bone strength in persons without cancer, but the effectiveness of resistance exercise programs on osteoporosis in cancer survivors is not yet known. Women who experience menopause during or after treatment and men with prostate cancer who are treated with long-term androgen-suppressive medications are at high risk for osteoporosis67,68 and might therefore benefit from resistance training to increase bone strength. Additional positive outcomes of exercise training can include improved lean body mass and balance, with resulting reduced risk for falls and subsequent fractures. Clinical trials are underway that are testing the effects of aerobic and resistance exercise on bone density in postmenopausal breast cancer survivors.
Cancer survivors with lymphedema may also benefit from exercise, specifically range-of-motion exercises, with approval from their treating physicians. The benefits and risks of resistance training in survivors with lymphedema have not been investigated systematically. There have been some concerns that physical activity involving the affected limbs might have adverse effects on lymphedema. However, results of an early pilot clinical and a small cohort study suggest that resistance training does not increase the risk for new or worsening lymphedema.69,70
No large clinical trials or observational studies have reported the effect of physical activity on the risk for cancer recurrence or survival, but several clinical trials have assessed the effect of physical activity on quality-of-life and other psychosocial outcomes in cancer survivors. The exercise programs in these trials were primarily 3 days per week of moderate to vigorous activity that was progressively increased in duration to approximately 45-minute sessions during a period of 3 or 4 months. These studies have shown that such exercise programs can reduce anxiety and depression, improve mood, boost self-esteem, and reduce symptoms of fatigue.14
Although some cancer survivors can adopt an exercise program independently, many will benefit from referral to an exercise specialist. A physical therapist is the appropriate resource for survivors with injuries, pain, or specific postsurgical issues such as lymphedema or amputation. Exercise physiologists receive college training and are certified by various professional organizations to develop individualized exercise programs. Personal trainers are also popular choices for persons who want to increase their fitness and activity levels. Personal trainers should have special training or certification, however, before working with cancer survivors.
In general, physical activity is likely to be beneficial for most cancer survivors. Recommendations on the type, frequency, duration, and intensity of exercise should be individualized to the survivor's age, previous fitness activities, type of cancer, stage of treatment, type of therapy, and comorbid conditions. Table 3 contains some suggested ways to increase physical activity.
Table TABLE 3. Suggested Ways To Increase Physical Activity
|• Use stairs rather than an elevator.|
|• If you can, walk or bike to your destination.|
|• Exercise with your family, friends, and coworkers.|
|• Take a 10-minute exercise break to stretch or take a quick walk.|
|• Walk to visit nearby friends or coworkers instead of sending an e-mail.|
|• Plan active vacations rather than only driving trips.|
|• Wear a pedometer every day and watch your daily steps increase.|
|• Use a stationary bicycle while watching TV.|
|• Plan your exercise routine to gradually increase the days per week and minutes per session.|
Particular issues for cancer survivors may affect or contraindicate their ability to exercise. Effects of treatment may also promote the risk for exercise-related injuries and adverse effects. Specific precautions should be heeded:
Survivors with severe anemia should delay exercise, other than activities of daily living, until the anemia is improved.
Survivors with compromised immune function should avoid public gyms and other public places until their white blood cell counts return to safe levels. Survivors who have completed a bone marrow transplant are usually advised to avoid exposure to public places with risk for microbial contamination, such as gyms, for 1 year after transplantation.
Survivors suffering from severe fatigue from their therapy may not feel up to an exercise program, so they may be encouraged to do 10 minutes of stretching exercises daily.
Survivors undergoing radiation should avoid chlorine exposure to irradiated skin (eg, swimming pools).
Survivors with indwelling catheters should avoid water or other microbial exposures that may result in infections as well as resistance training of muscles in the area of the catheter to avoid dislodgment.
Survivors with significant peripheral neuropathies may have a reduced ability to perform exercises that use the affected limbs because of weakness or loss of balance. They may do better with a stationary reclining bicycle, for example, than walking outdoors.
For the general population, the ACS and other health organizations recommend at least 30 minutes of moderate physical activity at least 5 days per week to reduce the risk for cancer, cardiovascular disease, and diabetes.16,20,22 These levels of activity have not been studied or tested specifically in cancer survivors, however. For the general population and for cancer survivors, any movement is likely beneficial. Therefore, although daily and regular activity may be preferred and may be a goal, any steps that are taken to move from a sedentary to an active lifestyle should be encouraged. For survivors wanting maximum benefit, the message should be that the health benefits of exercise are generally linear, with benefit related to higher intensity and duration, although extremely high levels of exercise might increase the risk for infections.71