CEACAM5 and neoplasm: For the 93 patients with perihilar cholangiocarcinoma (pCCA) who underwent surgical resection analyzed in this study, we retrieved the following clinical and biological features: age (≤ or >60 years), sex, tumor size (≤ or >2.5 cm), tumor differentiation degree, T staging, lymph node metastasis (LNM) status, M staging, AJCC8th TNM staging, preoperative serum carcinoembryonic antigen (CEA) (≤ or >4 ng/mL) value, carbohydrate antigen 19-9 (CA19-9) (≤ or >135 U/mL) value, HBV infection, and microscopic residual tumor (R0 or R1).