Primary Gallbladder Neuroendocrine Tumors: Insights into a Rare Histology Using a Large National Database

Primary gallbladder neuroendocrine tumors (NETs) are rare, poorly understood cancers infrequently encountered at even the largest of tertiary referral centers. We therefore sought to identify a large cohort of patients with gallbladder NETs using a national database, with the aim of defining treatment modalities employed and survival associated with these uncommon malignancies.

Patients with primary gallbladder NETs were identified in the National Cancer Database, and clinicopathologic characteristics were recorded. A univariate log-rank survival analysis was completed for patients who underwent resection. Parameters found to be significant were entered into a multivariate accelerated failure time analysis. For context, survival comparisons were included for patients who underwent resections for NETs at any gastrointestinal site and for gallbladder adenocarcinoma.

Overall, 754 patients with gallbladder NETs were identified. Patients were predominantly female (n = 518, 69%), White (n = 503, 67%), presented with stage IV disease (n = 295, 39%) and had high-grade lesions (n = 312, 41%). The majority underwent resection (n = 480, 64%), primarily simple cholecystectomy (n = 431, 90%), whereas a minority received multimodal therapy (n = 145, 21%). Among patients who underwent resection, older age (p = 0.001), large cell histology (p = 0.012), and positive margins (p = 0.030) were independently associated with worse overall survival. Patients with gallbladder NETs had improved survival relative to those with gallbladder adenocarcinoma (p = 0.001), but significantly worse survival than patients with NETs from other gastrointestinal sites (p < 0.001).

Primary gallbladder NETs are aggressive lesions that carry a worse prognosis than NETs of other gastrointestinal sites. Older age, positive margins, and large cell histology are associated with abbreviated survival after resection.