PDCD1 and neoplasm: In a retrospective cohort of 34 patients with advanced HNSCC treated with PD-1/PD-L1 inhibitors, Saâda-Bouzid et al. used the tumor growth kinetics (TGK), which is the difference of the sum of the largest diameters of the target lesions (according to RECIST) per unit of time between two evaluations [15].