PDCD1 and cancer: Although there have been several bibliometric studies related to PD1 or PDL1, they usually only focused on some specific aspects such as documents on PD1/PDL1 molecule, anti-PD1/PDL1 therapy in China or for a single kind of cancer (Zhao et al., 2018; Baş and Şenel, 2019; Gao et al., 2019; Ahn and Hwang, 2020; Li et al., 2021).