Objective Definition and Optimized Strategy for "Biologically Borderline Resectable" Colorectal Liver Metastases.

Area of Science:

• Hepatobiliary Surgery
• Surgical Oncology
• Gastroenterology

Background:

• Neoadjuvant chemotherapy (NAC) is recognized for unresectable colorectal liver metastases (CRLM), but its benefit for resectable CRLM is unclear.
• Defining biologically borderline resectable (bBR) CRLM is crucial for optimizing treatment strategies.
• This study investigates the prognostic impact of NAC versus upfront surgery (UFS) for resectable CRLM.

Purpose of the Study:

• To assess the prognostic benefit of NAC for resectable advanced CRLM.
• To establish an objective definition for biologically borderline resectable (bBR) CRLM.
• To identify optimal indications for NAC in bBR-CRLM.

Main Methods:

• A bicentric retrospective analysis of 2007-2021 CRLM patients undergoing curative-intent liver resection.
• Development of a classification matrix using virtual hepatectomy and Beppu's nomogram to define bBR-CRLM.
• Propensity score matching to compare long-term outcomes of bBR-UFS and bBR-NAC groups.

Main Results:

• 240 of 831 patients were classified as bBR-CRLM (139 UFS, 101 NAC).
• Biological Conversion occurred in 10% of bBR-NAC patients, showing significantly longer overall survival.
• After propensity score matching, no significant difference in long-term outcomes was observed between bBR-UFS and bBR-NAC groups.

Conclusions:

• NAC for bBR-CRLM generally does not improve prognostic impact after liver resection.
• A small subset of patients experiencing Biological Conversion may benefit from NAC.
• NAC is not broadly indicated for resectable bBR-CRLM outside of specific conversion cases.