Benchmarking Oncologic Outcomes of Liver Resection for Colorectal Metastases

OBJECTIVE: The present study aims to establish reference standard values for liver resection outcomes in patients with colorectal liver metastases (CRLM) across different tumor burdens. BACKGROUND: Liver surgery has long been the only potentially curative treatment for CRLM, but now options are rising, such as thermal ablation for patients with small oligonodular lesions and liver transplantation for those with high tumor burden. Elucidating surgical outcomes of resective surgery is crucial to defining its role. METHODS: All patients included in the LiverMetSurvey registry between 2000 and 2022 were considered. Only patients undergoing complete resection in high-volume centers without extrahepatic disease and with follow-up >1 year were included. The analyzed outcomes were: 90-day mortality, and 1, 3, and 5-year overall survival (OS) and recurrence-free survival (RFS). Patients were divided into subgroups based on tumor burden, and the analysis was restricted to "benchmark" patients, selected on preoperative chemotherapy administration and response. RESULTS: Overall, 12154 patients treated across 43 centers were enrolled. Ninety-day mortality rate was <5% for most groups. Benchmark value for one-year OS rate exceeded 85% across all subgroups, except for patients with 10 or more CRLM (≥78%). Benchmark values for 5-year OS rates were: ≥45% for solitary synchronous metastases and ≥58% for solitary metachronous ones (if ≤30 mm, ≥54% and ≥67%, respectively); ≥48% for 2 to 3 metastases; ≥28% for more than 3 metastases; and ≥29% for initially unresectable disease. Benchmark values for 5-year RFS rates were: ≥22% for solitary synchronous metastases; ≥36% for solitary metachronous ones; ≥21% for 2 to 3 metastases; ≥15% for 4 to 9 metastases; ≥4% for 10 or more metastases; and ≥10% for initially unresectable disease. CONCLUSIONS: Liver resection has an excellent oncologic effectiveness, even in patients with severe tumor burden. The reference standard values for key oncologic outcomes should serve as benchmarks for evaluating and testing alternative treatments.