Changes in diet, physical activity, and supplement use among adults diagnosed with cancer. (Research).

Approximately 1,285,000 Americans will be diagnosed with cancer in 2002 (1). Although cancer is generally thought of as a life-threatening disease, survival rates have improved dramatically for many malignancies (2). For example, five-year survival in the United States is about 80% for prostate and breast cancers and 60% for colorectal cancer (1,3), and the National Cancer Institute estimates that approximately 8.9 million Americans with a history of cancer were alive in 1997 (1).

Life-threatening health events such as a diagnosis of cancer may prompt psychological distress that motivates individuals to reduce risk (4,5). The experience of cancer diagnosis and treatment is difficult and may serve as a critical cue for an individual to undertake future health promotion activities (6). In a survey of 1,667 cancer survivors, Demark-Wahnefried and colleagues reported that there was a strong interest in health promotion programs aimed at healthier diets, exercise, and smoking cessation (7). The major role of a dietetics professional in relation to cancer patients is often nutritional status assessment and support during the early phases of treatment and recovery. However, nutrition interventions may be beneficial to cancer survivors during the health maintenance phase of cancer, in which the goals are improved quality of life as well as preventing cancer recurrence, second primary tumors, and other preventable diseases (8).

Data regarding changes in lifestyle in response to a diagnosis of cancer are scarce. This report examines self-reported changes in diet, physical activity, and dietary supplement use among cancer patients diagnosed up to 24 months in the past. We investigate whether patients felt that these changes improved their health and well-being and identify sociodemographic, clinical, and selected psychosocial characteristics that predict these lifestyle changes.

METHODS

Overview and Study Participants

Participants were identified from the population-based Cancer Surveillance System, which is part of the National Cancer Institute's Surveillance Epidemiology and End Results program (9). The registry catchment area includes 13 counties in western Washington state. We obtained permission from each patient's physician before sending a letter of invitation to participate in the survey, which was followed up by a telephone call approximately one week later. We made at least 15 attempts to contact patients by telephone. Trained interviewers used a computer-assisted telephone interview system to administer a structured questionnaire. Interviews were conducted between February and July of 1999. The protocol for the study was approved by the Institutional Review Board of the Fred Hutchinson Cancer Research Center.

Eligible participants were English-speaking patients, aged 20 to 79, diagnosed with first primary invasive breast, prostate, or colorectal cancer between February 1997 and December 1998. We chose to examine these cancers because they are the major ones affecting Americans that also have high survival rates (1). We randomly selected a sample of 511 adult patients to obtain approximately equal numbers of breast, prostate, and colon cancers such that half were diagnosed within the previous 11 months and the other half were diagnosed 12 to 24 months before sampling. Two patients were ineligible because they did not speak English, and five patients were deceased. We completed interviews with 356 (70.6%) of 504 eligible participants. Reasons for nonparticipation were physician refusal (5.0%), inability to locate (7.9%), patient refusal (15.3%), and illness (1.2%).

Changes in Diet, Physical Activity, and Supplement Use

Each patient was asked to report on lifestyle changes made in the past 12 months, For all changes made, each respondent was asked whether he or she strongly agreed, agreed, disagreed or strongly disagreed with the following statement: "This has improved my physical and mental well-being."

Diet Each patient was asked if he or she had made any major changes in dietary intake that were aimed at coping with cancer or reducing the risk of cancer spreading or returning. If yes, the patient was asked to specify the dietary changes. Interviewers coded the response(s) from a list of options: (a) became a vegetarian; (b) ate more fruits and vegetables; (c) ate less red meat; (d) ate less fat; (e) ate more healthy in general; (f) fasted; (g) juiced; (h) used special supplements such as Ensure, Boost, or protein powders; (i) followed a weight-loss diet; or (j) other. The exact text of "other" responses was entered into computers by interviewers. More than one response was allowed. This method of assessing recent change in consumption has proven useful in other studies of trends in diet (10,11).

Physical activity Each patient was asked if he or she had begun physical activities in the past 12 months that were aimed at coping with cancer or reducing the risk of …