Historically, under-nutrition and cancer-related cachexia were the primary nutritional concerns among cancer patients. While these issues are still important for survivors of gastrointestinal (GI) related-malignancies and head and neck cancers, as well as those with advanced disease, being overweight is fast becoming the more common concern due to earlier stage at diagnosis and the prevalence of obesity-related cancers (e.g., cancers of the breast, prostate and colorectum). In general, the ACS guidelines and the new research indicate that being overweight is associated with cancer recurrence, cancer mortality, or preventable mortality from other causes. Below, we recapitulate the ACS dietary guidelines for underweight and then overweight cancer survivors.
For patients who are underweight (and often weak, easily fatigued, and suffering from poor quality-of-life), the ACS guide describes the goal of achieving “positive energy balance,” (i.e., to consume more energy than that expended to promote weight gain) with the expectation that this will hasten healing and prevent co-morbid medical complications.6
Changes in taste, smell, and the integrity and function of the oral mucosa that accompany advanced disease and some forms of treatment, can impair appetite and the consumption of adequate energy. Thus for these patients, the ACS guide recommends energy-dense foods that are easy to chew and swallow, and mild in flavor.6
Aversions to meat and other foods, can pose challenges to adequate consumption of energy and protein; food-related preferences often serve as a moving target. In general, cold foods and reliance on protein sources other than red meat, (i.e., dairy, legumes, poultry, and fish are best-accepted).6
Also, given that undernourished patients are frequently immunosuppressed, food safety issues are of paramount concern and call for careful food preparation methods. The ACS guidelines strongly suggest the referral of these patients to a registered dietitian, especially those who cannot eat or those who have already tried and failed to gain weight with dietary changes on their own.6
Readers wanting specific recommendations for underweight patients who are currently receiving cancer treatment or at the end-of-life are referred to the ACS guide.
Although underweight is an acknowledged problem among a defined sector of cancer survivors, a large body of literature has emerged which correlates overweight and obesity with health risk for cancer survival.14
In the ACS guide, seven studies are reviewed which report associations between overweight or obesity and increased risk of cancer recurrence or mortality.6
In a prospective study of 900,000 U.S. adults, Calle and colleagues found that overweight and obese individuals diagnosed with cancer had significantly higher rates of mortality from non-Hodgkin’s lymphoma, multiple myeloma, and from cancers of the esophagus, colon and rectum, liver, gall bladder, pancreas, kidney than cancer patients of normal weight; significant trends for increased risk also were found for cancers of the breast, uterus, cervix and ovaries in women; and prostate and stomach in men.19
A recent review by Demark-Wahnefried and Moyad concluded that there is strong evidence to suggest that an increased body mass index (BMI) at the time of diagnosis is associated with poorer prostate cancer outcomes, since eight of nine studies have shown this relationship.20
In another review of obesity and prostate cancer outcomes, Freedland and Platz report on eight of 10 studies that found significant associations between increased BMI and poorer prostate cancer outcomes, with all nine studies finding a significant association between increased BMI and prostate cancer mortality.21
Five of six new studies, located in our search of weight status and cancer recurrence (see .), use epidemiological methods to investigate the relationship between weight, at the time of cancer diagnosis, and health outcomes.7, 9–12
In these studies, large populations of cancer survivors were followed for 5 to 11 years to evaluate recurrent cancer, increased cancer mortality, or poorer overall survival. In all five studies, overweight or obesity at the time of cancer diagnosis was significantly associated with poorer cancer or overall health outcomes. Findings from these studies present a fairly consistent picture: (a) increased BMI at the time of breast cancer diagnosis is correlated with poorer cancer outcomes;7, 9, 10
(b) increased BMI at the time of prostate cancer diagnosis is found to be associated with poorer prostate cancer outcomes;12
and (c) BMI greater than 35 was strongly associated with recurrent colon cancer and increased colon cancer mortality.11
In contrast, research related to weight gain after diagnosis has produced mixed results8
with several studies cited in the ACS guide suggesting that weight gain has an adverse effect on recurrence and survival (disease-free or overall)6
and more recent studies (see ) suggesting no associations with disease-specific survival.
There are three important implications for nursing practice that emanate from the ACS guidelines and the newer literature on body weight and cancer survival. First, nurses should recognize that roughly two thirds of U.S. adults are classified as overweight or obese.22
Second, nurses should consider the concept of “body mass index-years,” to conceive of the cumulative risk of years lived overweight (much as they already consider cigarette smoking “pack years”).21
Most importantly, oncology nurses should educate their patients that being overweight may increase the risks of cancer recurrence and cancer mortality, and is certainly a risk factor for prevalent co-morbidities among survivors that contribute to overall mortality. In addition to providing this important message, nurses should be ready to point patients to appropriate resources, i.e., registered dietitians and approved weight management programs, and also practice weight management themselves, so they can lead their patients by example.
For patients that recognize the need to lose weight, the ACS guidelines spell-out three weight loss strategies. First, patients should consult with their oncologist before starting any diet or exercise program.6
Second, patients should be guided toward sound weight management strategies, i.e., well balanced, lower calorie diet that promotes a weight loss of no more than two pounds per week (this rate assures that patients avoid nutritional deficiencies from over-rapid weight loss and also maximizes the proportional loss of fat as opposed to lean tissue).6
And finally, though not a nutritional recommendation per se
, nurses should encourage patients to exercise as a key component in weight management and practice appropriate behavioral management skills to achieve dietary and exercise change.6
In summary, for overweight and obese cancer survivors, a thoughtful plan for weight reduction will likely reduce prevalent co-morbidities within this population and may ultimately impact cancer recurrence and mortality.
DIET COMPOSITION AND SPECIFIC FOOD CHOICES
The idea that food choices (i.e., learning to avoid some foods or to increase the consumption of others) could improve cancer prognosis has been a hope and a research goal for some time. It is well-known that cancer survivors are at increased risk for chronic illnesses, such as diabetes and heart disease; it is also well-known, and repeatedly emphasized in the ACS report, that a healthy, well-balanced diet can prevent or at least reduce the severity of these chronic conditions.6
However, as stated previously, because cancer survivorship is a fairly new concept, only a few studies have been undertaken in this area and the data are minimal and tend to be unstable. To date, most studies have been observational in nature; however two major randomized control trials (RCTs) were undertaken in breast cancer survivors to test the potential benefit of a low fat diet and a diet very high in fruits and vegetables in combination with dietary fat restriction. These results were released just recently, (after the ACS report) and we have assimilated these findings into the following discussion. While the consumption of specific foods is of interest in relation to disease, it should be recognized that dietary patterns (i.e., the global nature of the diet) may have more importance.23
A key study cited in the ACS report was one by Kroenke and colleagues24
on breast cancer survivors identified in the Nurse’s Health Study cohort which found that a well-balanced diet (i.e., a low fat, plant-based diet), was significantly associated with overall survival, but not cancer-free survival. A more recent study by Meyerhardt et al. of 1009 stage III colon cancer survivors found that those who consumed a “Western” diet (increased amounts of red meat and regular dairy products and decreased fruits, vegetables and whole grains) had a higher recurrence of colon cancer and an increased colon cancer mortality than those who consumed a “Prudent Diet” (increased fruits, vegetables, whole grains and low fat dairy products and less red meat).16
Recent findings reported by McEligot et al.17
and Fink et al.18
are inconsistent. McEligot et al determined that less fatty diets were associated with decreased overall mortality17
while Fink et al found no correlation between diet and survival.18
Another study of low fat, high fruit and vegetable diets in lung cancer survival revealed no significant associations between the diet and survival, though the sample used in this study was relatively small.13
In addition to this new, epidemiological research, eagerly anticipated results from two randomized clinical trials of diet composition and cancer survival were published since the ACS report. The first of these was the Women’s Intervention Nutrition Study (WINS) in which, cancer recurrence was studied in a group of 2437 early stage, postmenopausal breast cancer patients receiving conventional cancer treatment and who were randomly assigned to an intervention arm (n=975), that received individual and group class instruction to reduce dietary fat to 15% of total calories or to a control arm (n=1462), that received counseling to consume a well-balanced diet. Study participants were followed an average of 5 years.25
Patients who received the dietary intervention, versus those in the control arm, experienced a 24% reduction cancer recurrence (P=.034), an effect which was significantly stronger among patients diagnosed with estrogen-receptor negative (ER−) disease, as compared to those who were ER+. 25
It should be noted that study participants in the low fat arm experienced a mean weight loss of six pounds and it is unknown whether the benefit observed in this trial was linked more to the low fat diet or to the loss in body weight.
In a second RCT, entitled WHEL (Women’s Healthy Eating and Living) study, 3088 pre- and – post-menopausal breast cancer survivors within 4-years of diagnosis of stage I-IIIA disease who received standard cancer care were randomly assigned to: (a) an intervention arm (n=1537) that received a dietary intervention (telephone counseling, cooking classes, and a newsletter) to consume a daily diet of 5+ vegetable servings, 3+ fruit servings, 16 oz of vegetable juice, 30 grams of fiber, and a reduction in fat to 15–20% of total Calories; (b) a control arm (n=1551) who received print material only about basic nutrition.26
While WHEL participants in the intervention arm achieved the stringent dietary goals promoted in the study; no significant benefit in breast cancer outcomes was observed. Intuitively, one would have expected the WHEL diet to have resulted in weight loss for intervention subjects. It did not. In an editorial that accompanied the WHEL main outcomes paper, Gapstur and Khan discuss the somewhat conflicting findings of the WINS and WHEL studies.27
They suggest that the absence of weight loss in the WHEL intervention, in contrast to that observed in WINS, may explain the absence of benefit.27
Other reasons may be that a high proportion of women enrolled in the WHEL study were already following a diet which included ample servings of fruits and vegetables and which was low in fat, thus no effect may have been possible. Gapstur and Khan conclude that the “high level of obesity, weight gain or both after diagnosis is adversely associated with breast cancer disease-free survival and overall survival.”27
This may be an overriding factor. Of interest, in another study by Pierce et al. that was conducted solely on the women participating in the control arm of WHEL, the strongest association between breast cancer outcomes and lifestyle factors existed for physical activity, an association that was independent of body weight status or fruit and vegetable consumption15
. That said, it is of paramount importance for nurses to appreciate that with more and more cancer patients surviving their cancer, it is not only cancer-specific outcomes that are important, but those related to overall health. Thus, the recommendations put forth in the ACS report (see ), are instrumental in informing nursing practice aimed at improving the overall health of cancer patients
To help patients identify the right balance of foods, the ACS guide identifies three elements in food choice behavior. One, the guidelines state that fat should be restricted to 20%–35% of total dietary intake.6
Specifically, the ACS guidelines stress that saturated fat should be restricted to less than 10% of calories and trans-fatty acids should be limited to less than 3% of calories. The ACS dietary guidelines emphasize protein intake for survivor health and promote a diet that derives 10%–35% of calories from protein, or about 0.8g/kg body weight.6
For most US cancer survivors, the under-consumption of protein is not an issue; instead and more relevant is the substitution of healthier sources of protein, such as fish, poultry, beans and low fat dairy products to take the place of more commonly consumed high fat dairy products, and meats that are fatty and/or processed. Third, a variety of carbohydrates should make-up 45%–65% of total daily caloric intake.6
Nutrient dense carbohydrates, such as vegetables, fruits and whole grains, are encouraged (see ).