Nutrition During and After Cancer Therapy
Nutrition During and After Cancer Therapy
In 2008, roughly 1.44 million Americans were diagnosed with cancer, and accordingly were labeled as “cancer survivors.” Fortunately, for roughly 65% of those who were newly diagnosed, this label will expand to encompass issues of long-term survivorship and health maintenance. Extended cancer survivorship is a relatively new concept. In the past, most people who were diagnosed with the disease did not survive it. While longer survival times are a measure of success, the dark side of this victory is that a substantial proportion of these survivors will experience recurrence or second cancers. In addition, many more will go on to develop comorbid conditions such as cardiovascular disease (CVD), diabetes, or osteoporosis, which often kill or debilitate survivors at much higher rates than the cancer itself.[3,4]
Evidence exists that lifestyle factors, such as diet and physical activity, may make a difference not only in preventing the primary risk of cancer but also in improving quality of life and ameliorating symptoms. There also is evidence that nutritional status may influence the course of disease and affect cancer progression.[5,6] Given that dietary needs change for most persons as they move through the cancer continuum, oncology nurses apprised of current guidelines are best positioned to aid those under their care in making better food choices and paying heed to weight management.
The first nutrition guidelines that specifically addressed cancer survivors were established by the American Cancer Society (ACS) in 2003, and were updated 3 years later.[7,8] In 2007, the American Institute for Cancer Research (AICR), in collaboration with the World Cancer Research Fund (WCRF), also issued dietary guidelines for cancer prevention and extended these to cancer survivors. Both the ACS and the WCRF/AICR guidelines are based heavily on recommendations for primary cancer prevention, and share many commonalities with those established for the prevention and management of other prevalent chronic diseases, such as CVD and diabetes. Both sets of guidelines also include recommendations for physical activity, which, for the most part, are outside of the scope of this article, except for a discussion of the key role that physical activity plays in weight management. Tables 1 and 2 provide guideline summaries from each organization.
This article will address nutrition-related aspects of cancer survivor care from the point of diagnosis to long-term survivorship, including issues of appetite loss and inadequate food intake common with some cancer treatments, and extending to weight-related problems and comorbid conditions that cancer survivors share with the general population. It also will examine the need for interventions, and what is currently known (or not known) about how best to deliver them. The time of cancer diagnosis has been identified as a “teachable moment” when a high proportion of cancer survivors are hungry for nutrition information; it is a prime opportunity for the astute practitioner to kick-start the practice of lifestyle behaviors that can promote lifelong health benefits.
Unintentional Weight Loss
For patients who are underweight, the overall goals for nutritional care are to prevent or reverse nutrient deficiencies, to preserve lean body mass, to minimize nutrition-related side effects (such as reduced appetite, changes in taste and smell, difficulty swallowing, and nausea or vomiting), and to maximize quality of life. During cancer treatment, substantial weight loss, especially among patients of normal or lower body mass index, is associated with poorer treatment tolerance and outcomes, and poorer quality of life. Patients with lung, head and neck, and specific gastrointestinal cancers are most at risk for weight loss and adverse events stemming from undernutrition. Dietary counseling among these patients, in particular during the time of treatment, has been shown to improve outcomes.[8,10]
For added calories, consumption of more energy- and nutrient-dense foods (such as peanut butter, yogurt, dried fruit, avocados, cheese, granola, legumes, and eggs) is recommended. Smaller, more frequent feedings can be helpful in obtaining adequate energy. While mouth sores may impede consumption of foods that are either chemically or physically abrasive (eg, citrus or tomato-based foods, tortilla chips), soft, bland foods and casseroles are usually well-tolerated. For those unable to eat enough solid food, several liquid supplements are commercially available that can provide much-needed nutritional support, without carrying the food safety risks of homemade formula. The ACS guidelines strongly suggest referral of cancer patients to a registered dietitian (contact the American Dietetic Association at www.eatright.org “Find a Nutrition Professional”), especially patients who cannot eat or those who have already tried and failed to gain weight.
Problems Related to Weight Gain
At the other end of the spectrum, overweight and obesity also can undermine the overall health and survival of the patient with cancer. First of all, overweight and obesity are well-established risk factors for cancers of the breast (postmenopausal), colon, kidney, and endometrium, and the list of obesity-related cancers grows as data continue to accumulate. Therefore, a substantial proportion of cancer patients are overweight or obese at the time of diagnosis. Case in point, the prevalence of overweight and obesity (BMI >24.9) exceeds 70% in the two largest segments of cancer survivors, ie, survivors of breast and prostate cancer. Second, data show that increased body weight at the time of diagnosis is associated with increased mortality (overall and cancer-specific) for all cancers combined, and specifically for non-Hodgkin’s lymphoma and multiple myeloma, and cancers of the breast, esophagus, colon and rectum, cervix, uterus, liver, gallbladder, stomach, pancreas, prostate, and kidney.