Presenter: Shekhar Gogna MD | Westchester Medical Center Background: Primary gallbladder neuroendocrine tumors (GB - NET) are very rare. Although there are other numerous studies of neuroendocrine tumors, few case series describing primary GB-NET exist. Methods: This is a retrospective analysis of the SEER database from 1973 – 2016. The epidemiological trend was analyzed using the Joinpoint regression analysis. Survival was assessed with Kaplan-Meier analysis and Cox-regression was used to assess predictors of poor survival. We also utilized the artificial neural network to assess the discriminatory power of significant variables on Cox regression and to assess the individual variable important in predicting survival. Results: A total of 329 patients with GB-NET were identified from the SEER database. The mean age at diagnosis was 65.39 ± 14.32 years. Females outnumbered males (66.3 % vs. 33.7 %) and whites were the predominant race included (79.6 %). The Joinpoint nationwide trend analysis shows a rising trend of this tumor pathology by 7 % per year from 1973 to 2016 (Figure I). The mean survival time after diagnosis of GB-NET was 43.11 ± 58.80 months (0 – 239 months). The most common pattern of nodal metastasis pattern was N0 (57.1 %), followed by N2 (15.8 %), and N1 (10.7 %), with survival mirroring nodal status (p <0.01). Patients who underwent surgery had a significant survival advantage (105.50 ± 6.93 months compared with 7.32 ± 1.53 months, p<0.01). Cox- regression analysis showed advanced age (HR 1.03, p<0.01), tumor extension (HR 5.16, P < 0.01) and histopathological grade (HR 3.15, P < 0.01) of the tumor being associated with higher mortality. The artificial neural network model showed that the tumor grade had the highest predictor for mortality. Conclusion: GB-NET is a rare histopathological type of gallbladder cancer, that is displaying a rising incidence in the US. The high incidence of localized disease in simple cholecystectomy specimens suggests that discovery after gallbladder surgery may be contributing to the rising histological identification. Surgical resection is associated with a significant survival advantage. Advanced age, tumor extension and histopathological grade of the tumor are associated with higher mortality.