We found that high muscle density, as determined by lumbar CT images taken just before the initiation of PD‐1/PD‐L1 inhibitor therapy, was significantly associated with a high ORR and long PFS duration, irrespective of the degree of PD‐L1 expression in the tumor and PS, both of which are established predictors of efficacy in these treatments. This evidence concerns the gene PDCD1 and neoplasm.