GDF15 and non-small cell lung carcinoma: A significant association between circulating GDF‐15 and loss of body weight, skeletal muscle and adipose tissue was identified at relapse in an exploratory proteomic analysis of circulating putative mediators of cachexia, performed in a subset of 110 individuals from TRACERx, a prospective multicentre study of participants with primary non‐small‐cell lung cancer (NSCLC).4