Energy expenditure in malnourished gastrointestinal cancer patients

Cancer cachexia, a common finding in patients with gastrointestinal (GI) malignancy, is frequently attributed to tumor-induced aberrations in host energy expenditure. To characterize the frequency and severity of aberrations in energy expenditure in GI cancer patients, and to identify the potential influence of tumor characteristics in this group, the authors measured resting energy expenditure (REE) by indirect calorimetry in 173 patients and compared REE to predicted-energy expenditure (PEE) from the Harris-Benedict formulae based on current body weight. Fifty-eight percent of patients had abnormal REE (normal REE = +/- 10% PEE); 36% (62 of 173) were hypometabolic (REE less than 90% PEE), and 22% (39 of 173) were hypermetabolic (REE greater than 110% PEE). Host and tumor factors were compared between metabolic groups to identify potential determinants of abnormal energy expenditure. Differences between groups cannot be explained by differences in patient age, sex, body size, nutritional status, tumor burden, or duration of disease. Resting energy expenditure does not correlate with percent of weight loss, serum albumin, or duration of disease. Analysis by tumor site reveals patients with pancreatic or hepatobiliary tumors to be predominantly hypometabolic; gastric cancer patients tend to be hypermetabolic, whereas patients with colorectal or esophageal neoplasms are more evenly distributed across metabolic groups, the largest portion being normometabolic (X2 = 20.7, P less than 0.02). The majority of GI cancer patients have abnormal REE which is unpredictable and not uniformly hypermetabolic. The determinants of these abnormalities do not appear to be age, sex, body size, nutritional status or tumor burden. Primary tumor site is a major determinant of energy expenditure in GI cancer patients.