GDF15 and cancer: Recent studies have found several diagnostic biomarkers for loss of muscle mass such as N‐terminal peptide of procollagen type III, C‐terminal agrin fragment, leptin, ghrelin, and obestatin6, 7 and prognostic biomarkers in cancer patients such as matrix metalloproteinases, survivin, and butyrylcholinesterase.8, 9, 10 Although GDF15 might also be a useful prognostic marker in cancer patients, the small sample size, the heterogeneous population, and the selection bias could have some impacts on the findings in this study.