VSIR and colorectal cancer: Recent studies demonstrate that high PD-1H expression correlates with a favorable prognosis in patients with colorectal cancer, high-grade serous ovarian cancer, triple-negative breast cancer, hepatocellular carcinoma, and esophageal adenocarcinoma (Zhang et al., 2018; Loeser et al., 2019; Cao et al., 2020; Zong et al., 2020; Zong et al., 2021).