Although trials were initially undertaken in NSCLC, the progression of ICI use into other tumor types has seen the expansion of PD-(L)1 PET tracer studies into squamous cell carcinoma of the head and neck, breast cancer, renal cell carcinoma, diffuse large B-cell lymphoma, melanoma, and other cancers (Figure 2 and Supplementary Table 2). This evidence concerns the gene CD274 and non-small cell lung carcinoma.