Surgical practice patterns and outcomes in T2 and T3 gallbladder cancer: insights from a population based study

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Tharmalingam, Senthuran
Gallbladder Cancer , Extended Resection , Population-Based Study , Overall Survival
Background: Gallbladder cancer (GBC) is a lethal malignancy. Surgery remains the only option for cure. Our study aimed to evaluate practice patterns in patients with stage T2 and T3 GBC and describe the association between the extent of surgical resection and overall survival. Methods: This was a population-based cohort study from 2002-2012 including all cases of GBC in Ontario identified using the Ontario Cancer Registry (OCR). Those who underwent surgical resection were identified using linked administrative datasets and their pathology reports were abstracted to identify T2 and T3 GBCs. Type of surgical resection was classified as ‘extended’ (cholecystectomy + liver resection and/or bile duct resection) or ‘simple’ (cholecystectomy only). The association between type of surgical resection and OS was explored using Cox proportional hazards regression models. Results: 232 cases of T2 and 138 cases of T3 GBC were identified with 24% (56/232) of T2 cases and 37% (51/138) of T3 cases receiving extended resection. Unadjusted overall 5-year survival for simple vs extended resection was 39.7% vs 49.5% for T2 GBC (p =0.03) and 13.5% vs 22.8% for T3 GBC respectively (p=0.05). In T2 adjusted analysis, extended resection was associated with improved overall survival (OS) (HR = 0.51; 95% CI 0.30 -0.97, P = 0.01), while poor differentiation (HR = 3.42; 95% CI 1.92 -6.08, P = 0.0001), presence of lymphovascular invasion (HR = 1.75; 95% CI 1.16 -2.64, P = 0.03), and positive lymph nodes (HR = 1.78; 95% CI 1.03 -3.08, P = 0.03) was associated with worse OS. In T3 adjusted analysisc, only female sex (HR = 0.66; 95% CI 0.43-1.00, P = 0.05) was a predictor of improved OS, while older age (HR = 1.04; 95% CI 1.02-1.04, P = 0.0005) was associated with worse OS. On stratified analysis, extended resection demonstrated a trend towards improved survival in node negative cases only (HR=0.20; CI 0.03-1.06, P=0.07). Conclusions: The use of extended resection for T2 and T3 GBC in Ontario is modest. Extended resection is associated with improved OS in all T2 disease and node negative T3 disease.
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