Exclusive liver invasion as prognostic indicator in T3 gallbladder cancer.

631 Background: T3 gallbladder cancer (GBC) contains a diverse range of invasive tumors. However, distinct prognostic outcomes may be observed among T3GBC confined to localized range despite sharing the same T3GBC. There is uncertainty regarding whether there are noticeable prognostic variances between tumors that invade the liver, or serosa only and those that extend to adjacent organs. This study aims to investigate prognostic differences according to the extent of invasion in patient with T3GBC. Methods: The patients with T3GBC who underwent curative intent surgery from February 2002 to December 2021 were analyzed. The patients were divided into those who had tumor invaded liver only, serosa only, or extended beyond. Their clinicopathologic characteristics, perioperative details and prognostic data were compared. Survival analyses were carried out using the log-rand test including subgroups considering nodal metastasis, and other T stages. Cox-proportional hazard model including other factors were used to identify the independent risk factors for survival. Results: We identified 194 patients with T3GBC. The patients with tumor invaded liver only, serosa only, and adjacent organs were 86, 33, and 35, respectively. The median survival was 23 months. The patients with invasion limited to the liver showed better survival than those who involve adjacent structures (26 months vs 9 months, p < 0.001). In multivariate analysis, it was demonstrated that the concomitant presence of invasion in structures other than the liver serves as independent prognostic factors for survival. (hazard ratio [HR], 6.8, 95% confidence interval [CI] 1.746 – 26.803, p = 0.006) as well as lymphovascular invasion (HR 2.5, 95% CI 1.093 – 4.193, p= 0.026 ). Conclusions: In the T3 gallbladder cancer, exclusive liver invasion is a better prognostic indicator compared to concurrent invasion around adjacent structure. It is crucial to recognize that the extent of invasion in T3GBC patients before surgery. Multicenter studies are needed for the definite results.