PDCD1 and neoplasm: Mechanistically, SCRT‐based or CRT‐based TNT converts an immunologically “cold” tumor microenvironment into a “hot” one: radiotherapy induces immunogenic cell death, enhances antigen presentation, increases tumour‐infiltrating lymphocytes, and up‐regulates PD‐L1, thereby augmenting the activity of PD‐1/PD‐L1 blockade.