PDCD1 and neoplasm: Indeed, many studies have confirmed the poor prognostic role of the tumor-infiltrating PDL-1, CTLA-4, PD-1, and FOXP3 immunological markers in BC tissue (Syed Khaja et al. 2017; Tahir et al. 2022; Monneur et al. 2018; Sun et al. 2023), however, the role of the circulating levels of these markers is still a debatable issue.