Review

Diet, exercise, and complementary therapies after primary treatment for cancer Lee W Jones, Wendy Demark-Wahnefried

Every year, more than 10 million people are diagnosed with cancer worldwide. In view of the substantial improvements in early detection and treatment, even more patients can expect to be alive 5 years after diagnosis. With improvements in longevity, the late-occurring adverse effects of cancer and its treatment are becoming increasingly apparent. Healthy lifestyle behaviours that encompass regular exercise, weight control, healthy nutrition, and some complementary practices—eg, support groups, imagery—have the potential to greatly reduce cancer-treatment-associated morbidity and mortality in cancer survivors and can enhance quality of life. Here, we aim to review the strength of evidence for recommendations for exercise, weight management, nutritional practices, and related complementary therapies; assess the perceived needs of cancer survivors for health information and how they can access this information; and discuss the resources available to oncology care providers and patients about healthy lifestyle behaviours. Overall, this review provides important information to oncology care providers who counsel their patients on preventive lifestyle practices to maximise health and longevity after a diagnosis of cancer.

Introduction More than 10 million people a year are diagnosed with cancer worldwide.1 With improvements in early detection and treatment, increasing numbers of patients can expect to be alive 5 years after they are diagnosed with cancer. These individuals will join the expanding number of cancer survivors, estimated at about 25 million.1 Although these numbers are encouraging, cancer is associated with several long-term health and psychosocial sequelae.1–4 Indeed, cancer survivors are a vulnerable population that has distinct healthcare needs.3 Data clearly show that cancer survivors are at greater risk of developing secondary malignant diseases and other conditions, such as cardiovascular disease, diabetes, and osteoporosis compared with general age-matched and race-matched populations.1–4 An early comparison by Brown and colleagues2 of the medical records for more than 1·2 million patients obtained from the Surveillance, Epidemiology, and End Results database (US National Cancer Institute) with those obtained from the US National Center for Health Statistics found that patients with cancer were significantly more likely to die from noncancer causes than were the general population (hazards ratio 1·37). Data obtained over the past decade have confirmed these findings.3,4 These competing causes of death and comorbid conditions are believed to result from cancer treatment, genetic predisposition, or common lifestyle factors (eg, not practising healthy diet [figure 1] and exercise behaviours).2 Hewitt and colleagues3 reported that cancer survivors are almost twice as likely to have at least one functional limitation, and in the presence of another comorbid condition, the odds ratio increases to 5·06 (95% CI 4·47–5·72). From an economic perspective, an analysis by Chirikos and co-workers5 indicated that “the economic consequence of functional impairment exacts an enormous toll each year on cancer survivors, their families and the economy at large”, findings that have been confirmed by others.6,7 On the basis of these http://oncology.thelancet.com Vol 7 December 2006

Lancet Oncol 2006; 7: 1017–26 Department of Surgery (L W Jones PhD, W Demark-Wahnefried PhD) and School of Nursing (W Demark-Wahnefried), Duke University Medical Center, Durham, NC, USA Correspondence to: Dr Lee Jones, Box 3624, Duke University Medical Center, Durham, NC 27710, USA [email protected]

trends, cancer survivorship is fast emerging as a major public health concern.4 A report by the US Institute of Medicine8 summarised the numerous health issues of cancer survivors and reviewed the potential benefits of lifestyle modifications. It then made recommendations to guide healthcare providers, patients’ advocates, and other stakeholders in improving the health and wellbeing of this rapidly expanding and high-risk population—a population that up to now has received relatively little attention in advocacy, education, clinical practice, or research.8 In this Review, we discuss pertinent studies published since the US Institute of Medicine report (from 2004 to 2006), and address: the strength of evidence for recommendations in areas of diet and exercise, with an emphasis on weight management and osteoporosis prevention, as well as diet and exercise-related complementary and alternative treatments; the perceived needs of cancer survivors for health information and the

Figure 1: Not following a healthy diet could contribute to comorbidity

1017

Review

preferred method of accessing this information; and the resources available to providers and patients about healthy lifestyle practices.

Health promotion for cancer survivors Weight management Positive energy balance (ie, calorie intake exceeds calories expended) and negative energy balance (ie, calorie expenditure exceeds calorie intake) are dual concerns in cancer populations. For some survivors, such as those diagnosed with select respiratory, gastrointestinal, or childhood cancers, or those living with advanced disease, anorexia and cachexia can be problems that persist after primary treatment.9 For these survivors, continued use of supportive-care therapies including dietary counselling, pharmacotherapy (eg, megestrol), or nutritional support is sometimes crucial for recovery and might enhance the ability to eat and to maintain adequate nutritional stores, which are important for functional status and wellbeing.9,10 Exercise might also help to increase appetite, relieve constipation, and improve quality of life in these survivors.11 However, as noted in the US Institute of Medicine report,8 although anorexia and cachexia are crucial in cancer care, obesity and overweight are problems that are much more prevalent in most cancer survivors.11–13 Obesity is a well-established risk factor for cancers of the breast (postmenopausal), colon, kidney (renal cell), oesophagus (adenocarcinoma), and endometrium;14 thus, many cancer survivors are overweight or obese at the time of diagnosis. Furthermore, increased bodyweight before cancer is diagnosed has been associated with cancer mortality for cancers of the breast, oesophagus, colon and rectum, cervix, uterus, liver, gallbladder, stomach, pancreas, prostate, and kidney; non-Hodgkin lymphoma and multiple myeloma; as well as all cancers combined.15 Finally, additional weight gain is common during or after treatment for various cancers, and can exacerbate risk for functional decline, comorbidity, and perhaps even cancer recurrence and cancer-related death.16–18 Whereas studies investigating the relation between weight gain after diagnosis and survival have been somewhat inconsistent,13,16–18 the largest study18 to date, of 5204 patients, suggested that breast-cancer survivors who increased their body-mass index by 0·5–2·0 kg/m² had a risk ratio of recurrence of 1·40 (95% CI 1·02–1·92), and those who gained more than 2·0 kg/m² had a risk ratio of 1·53 (95% CI 1·54–2·34); both groups also had significantly higher allcause mortality compared with survivors with a stable weight. In addition, several studies13,17 have reported that increased bodyweight after diagnosis negatively affects quality of life. This accumulating evidence of adverse effects of obesity on both cancer-related and overall health and physical function, should make weight management a priority for cancer survivors.13,17,19 This priority is substantiated through viable physiological mechanisms,20 and because the health issues of this population are 1018

overlaid on the pandemic of overweight and obesity increasing worldwide.20,21 Despite the adverse effects of obesity in cancer survivors, only five studies22–26 have assessed weight management in cancer populations, and all were done in women with breast cancer. Two of these studies23,24 were done mainly on survivors who had completed active treatment, and found that individual dietary counselling provided by a dietician was effective in promoting weight loss. One of the studies24 found that counselling by a dietician was most effective if combined with a specific, structured Weight Watchers programme that included exercise: at 12 months, patients in the control group had gained a mean of 0·85 kg (SD 6·0), whereas those who received counselling alone lost a mean of 8·0 kg (SD 5·5) and those who received counselling and followed the Weight Watchers programme lost a mean of 9·4 kg (SD 8·6). Many behavioural interventions that use a comprehensive approach to energy balance and that include both diet and exercise components have higher probability of being effective than do interventions that rely on either component alone.27 In their evaluation of a diet and exercise intervention in patients with early-stage breast cancer, which was started during treatment and continued until 1 year after diagnosis, Goodwin and colleagues25 found that exercise was the strongest predictor of weight loss. In view of evidence13,28–30 that sarcopenic obesity (gain of adipose tissue at the expense of lean body mass) is a side-effect of both chemotherapy and hormonal treatment, exercise (specifically resistance exercise) could be especially important for cancer survivors because it is considered the cornerstone of treatment for this disorder. Until more is known, cancer survivors should follow guidelines established for weight management in general populations, and include not only dietary and exercise components, but also behavioural treatment.31 With research suggesting that 71% of cancer survivors are overweight or obese, effective weight management interventions need to be developed for this needy population.19

Nutrition and diet Energy restriction As noted previously, weight management should be the uppermost nutritional priority for cancer survivors. Thus, for most cancer survivors who are overweight, energyrestricted diets are recommended.11,19 Moderate energy deficits of up to 1000 kcal (4184 kJ) a day can be achieved by concomitantly increasing energy expenditure (via exercise) and reducing energy intake. Energy restriction can be achieved by reducing the energy density of the diet by substituting low-energy density foods (eg, waterrich vegetables, fruits, cooked whole grains, soups) for foods that are higher in energy.32 This so-called volumetric approach enhances satiety and reduces feelings of hunger and deprivation that often serve to undermine energyhttp://oncology.thelancet.com Vol 7 December 2006

Review

restricted diets. Another strategy involves restriction of the portion sizes of energy-dense foods.32 Newly issued dietary guidelines24,21 for cancer survivors emphasise energy balance and generally endorse dietary recommendations that have been established for the primary prevention of cancer and other chronic diseases.

Balancing fat, protein, and carbohydrate intake Fat, protein, and carbohydrate all contribute energy 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 an adequate supply of nutrients. In general, the choice of foods and their proportions within an overall diet (ie, dietary pattern) might be more important than absolute amounts of food.11,13,21 Because cancer survivors are at high risk for other chronic diseases, the recommended amounts and type of fat, protein, and carbohydrate to reduce these disease risks is also relevant.11 A study33 of 2619 breast-cancer survivors participating in the Nurse’s Health study suggests that those who reported a high proportional intakes of fruits, vegetables, whole grains, and low-fat dairy products had significantly lower mortality from non-breast-cancer causes than did those who reported high proportional intakes of meat, refined grains, high-fat dairy products, and desserts.

Fat A review13 of the 14 studies to date that have assessed the relation between fat intake and survival after the diagnosis of breast cancer, has shown that the results are notably inconsistent. In prostate cancer, only one study34has explored the association between fat intake and survival, and found that saturated fat intake (but not total fat) was associated with worse survival. The Women’s Intervention Nutrition Study,35 and the ongoing Women’s Healthy Eating and Living study,36 will test whether a reduction in fat intake increases overall survival and reduces risk of recurrence in women diagnosed with early-stage breast cancer. Preliminary results from the Women’s Intervention Nutrition Study35suggest that women assigned to the low-fat diet group (