Evaluation of clinicopathological features and prognosis of patients with small cell carcinoma of gastrointestinal system origin.

Abstract

e16481 Background: Small cell carcinoma of gastrointestinal origin is a rare, highly aggressive neuroendocrine malignancy that can arise throughout the gastrointestinal tract. It is characterized by early dissemination and poor clinical outcomes compared with conventional gastrointestinal carcinomas. Due to its rarity, clinicopathological characteristics, treatment patterns, and prognostic factors remain poorly defined, underscoring the need for large population-based studies. In this study, we aimed to describe the characteristics of patients with small-cell carcinoma of the gastrointestinal tract. Methods: This retrospective cohort study analyzed Surveillance, Epidemiology, and End Results (SEER) database data to identify patients diagnosed with primary gastrointestinal small cell carcinoma between 2000 and 2022. Demographic, clinicopathological, and treatment variables were extracted for analysis. Survival outcomes were assessed using Kaplan–Meier estimates, and independent prognostic factors were evaluated through multivariate Cox proportional hazards regression. Results: We analyzed data from 2791 patients. Patients aged 60 years and older (71.6%) and male patients (57.5%) were more prevalent. The most common sites of small cell carcinoma in the gastrointestinal system were the colon (29%), pancreas (21.4%), esophagus (16.9%), and stomach (9.7%). The metastatic disease rate at diagnosis was 57.4%. 20.5% of patients underwent cancer-related surgery. 24.1% of patients received radiotherapy, and 61% received chemotherapy. In patients with metastases, the most common metastatic sites were the liver (51.3%), bone (12.4%), lung (11.9%), and brain (3.4%). 2118 (75.9%) patients died due to small-cell carcinoma of the gastrointestinal system. The median survival time was 8 months (95% confidence interval, 7.5-8.4). The 1, 3, and 5-year survival rates were 38.1%, 15%, and 11.8%, respectively. Factors affecting survival were evaluated using multivariate analysis, and the results were as follows: age (p = 0.171), gender (p = 0.111), origin (p = 0.193), tumor site (p = 0.001), surgery (p < 0.001), radiotherapy (p < 0.001), chemotherapy (p < 0.001), and initial stage (p < 0.001). Conclusions: Patients with gastrointestinal small cell carcinoma had a high rate of metastatic disease at diagnosis and a poor prognosis. Prognosis varied depending on the tumor site. Tumors of unknown primary site and liver origin had the worst prognosis. Primary tumor surgery, chemotherapy, and radiotherapy were identified as independent prognostic factors.