Survival benefit and optimal timing for re-resection in patients with gallbladder cancer: A National Cancer Database analysis.

614 Background: Often times, gallbladder cancer is diagnosed incidentally after cholecystectomy. Most patients will then undergo re-resection for potential residual disease, however overall survival (OS) benefit data in this scenario is variable. Further, limited literature regarding optimal time to re-resection exists. Prior studies found the optimal time to re-resection to be approximately 4-8 weeks after initial diagnosis; however, additional data is needed to further validate these findings. In this National Cancer Database(NCDB) analysis we compare OS in patients diagnosed with T1b – T3 gallbladder cancer who underwent re-resection and evaluate if time to resection impacts OS. Methods: We reviewed the NCDB for patients who had received initial cholecystectomy for gallbladder cancer and were subsequently eligible for re-resection based on tumor stage (T1b-T3 disease) from 2004-2018. We excluded patients with metastatic M1 disease and T0, T1a, T1, or T4 disease. Patients with re-resection were further subdivided into four cohorts based on time to re-resection: 0-4 weeks, 5-8 weeks, 9-12 weeks and >12 weeks. We used a Cox proportional hazards ratio to identify factors associated with worse survival and logistic regression to evaluate characteristics associated with re-resection. OS was calculated using Kaplan Meier curves. Results: 791 (5.82%) patients received re-resection of 13,601patients meeting inclusion and exclusion criteria. Cox proportional hazards analysis showed a Comorbidity Score of 1 was associated with worse survival. Patients with higher Comorbidity Scores (1,2, or 3) and treatment at comprehensive community, integrated or academic cancer programs were less likely to undergo re-resection (in comparison to community programs). Patients treated at an Urban facility or diagnosed from 2009-2018 were more likely to undergo re-resection. The cohort with no re-resection had the lowest median OS [17.61 months; CI 17.05- 18.20] and re-resection showed significantly improved OS [HR 0.87; 95 CI 0.77-0.98; p=0.02]. Significantly improved survival was noted when re-resection was completed at 5-8 weeks [HR 0.67; CI 0.57- 0.81], 9-12 weeks [HR 0.64; CI 0.52- 0.79], or >12 weeks [HR 0.61; CI 0.47- 0.78]. Conclusions: Despite the retrospective nature and small sample size of our study, the results are consistent with prior studies depicting a survival benefit with re-resection. Additionally, optimal timing to re-resection supports previous data showing a clear benefit at any time >4 weeks. However, there was no significant survival difference as to whether re-resection was completed at 5-8 weeks, 9-12 weeks, or > 12 weeks post initial cholecystectomy. Decreased post-operative inflammation and accurate staging at >4 weeks may account for improved survival with later re-resection; however, future investigations are warranted to delineate underlying causes.