Surgical Outcomes of Non-Benchmark Perihilar Cholangiocarcinoma: A Multicenter Study from High-Volume Centers in Japan.

Abstract

To evaluate short- and long-term surgical outcomes in non-benchmark (non-BM) patients with perihilar cholangiocarcinoma (pCCA) using a multicenter cohort from Japan. Benchmark (BM) criteria have been proposed to standardize surgical outcomes in complex hepatopancreatobiliary procedures. However, BM studies typically exclude patients with significant medical comorbidities or those requiring technically demanding procedures. As a result, the majority of real-world pCCA cases, classified as non-BM, remain underrepresented in the literature, and their outcomes are insufficiently characterized. Between 2014 and 2018, a total of 648 patients underwent curative intent resection for pCCA at six high volume centers in Japan. Among them, 412 patients (64%) were categorized as non-BM and 236 patients (36%) as BM according to established surgical and medical exclusion criteria. Perioperative and oncologic outcomes were analyzed and compared with benchmark thresholds previously reported in the literature. Non-BM cases were further stratified into surgical, medical, and dual subgroups for subgroup analysis. The median operative time (644 minutes), intraoperative blood loss (1185 mL), and postoperative hospital stay (31 d) exceeded BM thresholds. Nevertheless, most postoperative outcomes, including Grade B/C post-hepatectomy liver failure (16.7%), bile leakage (22.8%), and in-hospital mortality (2.9%), remained within benchmark reference values. The median overall survival was 46.0 months, with 1-, 3-, and 5-year survival rates of 85.8%, 55.0%, and 37.1%, respectively. Subgroup analysis revealed decreasing survival with increasing complexity: 5-year survival rates were 50.5% in medical, 34.1% in surgical, and 15.4% in dual non-BM patients. Notably, left trisectionectomy was associated with the highest mortality (9.5%) among all procedures. Despite increased surgical complexity and patient-related risk factors, non-BM pCCA patients can achieve acceptable perioperative and long-term outcomes when treated at experienced, high-volume centers. Stratification by non-BM subgroup provides meaningful prognostic insight and may help guide surgical decision-making in complex pCCA cases.