The effects of chemotherapy on energy metabolic aspects in cancer patients: A systematic review

Background & aims: Cancer survival rates have increased significantly creating more awareness for comorbidities affecting the Quality of Life. Chemotherapy may induce serious metabolic alterations. These complications can create an energy imbalance, worsening prognosis. The effect of chemotherapy on energy metabolism remains largely unknown. The purpose of this systematic review is to determine the impact of chemotherapy on energy metabolism, creating more insight in a patients' energy requirements. Methods: We identified relevant studies up to May 2nd, 2019 using PubMed and Web of Science. Studies including all types of cancer and stages were selected. Only patients that underwent chemotherapy whether or not followed by surgery or radiotherapy were selected. Maximum follow-up was set at 6 months. Resting energy expenditure (REE), measured by indirect calorimetry (IC) or predicted by the Harris-Benedict equation (HBEq), was our primary outcome. Results regarding body composition were considered as secondary outcome parameter. Results: 16 studies were selected, including 267 patients. Overall, a significant decrease in REE [-1.5% to -24.91%] 1-month post-chemotherapy was reported. Two studies on breast cancer conducted a 3 and 6-month follow-up and found an increase in REE of 4.01% and 5.72% (p <.05), revealing a U-shaped curve in the expression of REE. Changes are accompanied by (non)significant variations in body composition (Fatmass (FM) and Fatfree Mass (FFM)). HBEq tends to underestimate REE by 4.03%-27.1%. Conclusion: Alterations in REE, accompanied by changes in body composition, are found during and after chemotherapy in all cancer types and stages, revealing a U-shaped curve. Changes in FFM are suggested to induce variations in REE concomitant to catabolic effects of the disease and administered drug. HBEq tends to underestimate REE, stressing the need for adequate assessment to meet patients' energy requirements and support dietary needs. (C) 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.