If there is a solid tumor for which the applicability of PD-1/PD-L1 inhibitors is judged based on a biomarker other than the dMMR status such as PD-L1 expression and the biomarker is negative, dMMR testing is recommended, because PD-1/PD-L1 inhibitors are expected to be effective if the tumor is dMMR, as shown in Fig. 6. This evidence concerns the gene PDCD1 and neoplasm.