Treatment Outcomes in Metastatic Neuroendocrine Carcinoma of the Gallbladder: A Retrospective Analysis from a Tertiary Cancer Centre in India

Background: Neuroendocrine carcinoma of the gallbladder (NEC-GB) is an exceptionally rare and aggressive malignancy, accounting for < 1% of gallbladder cancers. Limited data exist on the clinical profile and treatment outcomes of metastatic NEC-GB, particularly from low- and middle-income countries. This study aimed to describe real-world treatment patterns and survival outcomes in patients with metastatic NEC-GB treated at a tertiary cancer center in India. Methods: This retrospective cohort study included consecutive patients with pathologically confirmed metastatic NEC-GB treated at a tertiary cancer centre in North India, between September 2018 and August 2025. Demographic, clinicopathologic, and treatment data were extracted from institutional records. Systemic therapy regimens, response rates (per RECIST 1.1), and survival outcomes were analyzed. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan–Meier methods. Results: A total of 103 patients with metastatic NEC-GB were identified. The median age was 54 years, and 68% were females. Most patients presented with regional lymphadenopathy(79%) and liver metastases(63%). First-line chemotherapy was administered to 60 patients (58%), with platinum-etoposide being the most common regimen(90%).Rest 43 (42%) patients were planned for best supportive care. The overall response rate (ORR) to first-line chemotherapy was 53%, and disease control rate (DCR) was 77%. Median PFS was 6.0 months(95% CI, 5.2–6.8 months),and median OS was 5.0 months (95% CI, 2.5–7.5). Patients receiving best supportive care had significantly poorer OS compared with those receiving chemotherapy (9 vs 2.1 months; HR, 5; p < 0.001). Second-line treatment yielded limited benefit (median PFS 3 months). Conclusions: Metastatic NEC-GB carries dismal prognosis but remains responsive to platinum-based chemotherapy with efficacy comparable to extensive-stage small-cell lung cancer. Given the modest survival outcomes, there is an urgent need for multicenter collaborative studies and exploration of immunotherapy and molecularly targeted approaches in this rare disease.