Rethinking stage IVB gallbladder cancer: Decoupling N2M0 from M1 via de-escalation, chemotherapy, and risk...

Area of Science:

• Oncology
• Surgical Oncology
• Gastroenterology

Background:

• The AJCC 8th edition classifies both N2M0 and M1 gallbladder cancer (GBC) as Stage IVB, leading to identical treatment approaches.
• This study differentiates N2M0 from M1 disease to refine treatment strategies and risk stratification.

Purpose of the Study:

• To re-evaluate the roles of chemotherapy and surgical quality in Stage IVB GBC.
• To establish a clinical risk stratification system (CRSS) for differentiating N2M0 and M1 disease.

Main Methods:

• Utilized the SEER database to identify Stage IVB GBC patients (2000-2022).
• Employed 1:3 propensity score matching (PSM) to balance baseline characteristics between N2M0 and M1 groups.
• Analyzed overall survival, determined optimal lymph node ratio (LNR), and validated a prediction model via bootstrap resampling.

Main Results:

• PSM analysis included 125 N2M0 and 343 M1 patients.
• N2M0 patients showed significantly better median overall survival (17 months) than M1 patients (9 months) (P=0.001).
• Survival advantage for N2M0 was contingent on adjuvant chemotherapy; untreated N2M0 patients fared worse than treated M1 patients (P=0.002). Extended resection offered no benefit for N2M0. A lower LNR (<0.875) predicted longer survival. A CRSS was developed with distinct survival tiers (22, 12, and 9 months).

Conclusions:

• N2M0 GBC is biologically distinct from M1 disease and warrants separate staging.
• For N2M0 GBC, prioritizing thorough lymph node dissection and mandatory adjuvant chemotherapy is crucial.
• Extended organ resection is not recommended for N2M0 GBC; focus should be on optimizing chemotherapy and lymph node management.