Abstract: Objective   To investigate the clinical characteristics and prognostic factors of limited-stage and extended-stage primary esophageal small cell carcinoma. Methods The clinical data and follow-up data of patients with primary esophageal small cell carcinoma admitted to Sichuan Cancer Hospital from January 2014 to April 2023 were retrospectively analyzed. Chi-square test was used to compare baseline data of patients with limited-stage and extensive stage. Kaplan-Meier method was used to plot the survival curves of patients with limited stage and extensive stage primary small cell esophageal carcinoma, and the comparison of survival rates between groups was performed by Log-Rank test. The prognostic factors affecting the overall survival of patients with limited-stage and extensive stage were analyzed by univariate COX regression statistics, and factors with P <0.05 were selected for inclusion in multivariate COX regression analysis, and independent factors for survival and prognosis of patients with limited-stage and extensive stage PESCC were screened out.      Result    Seventy-two patients were included in this study, including 49 patients in the limited-stage and 23 patients in the extensive stage. The median survival time of LD patients was 18.300 months and that of ED patients was 10.903 months, and there was significant difference in survival time between the two patients (χ2=4.745, P =0.029). The results of univariate analysis showed that the prognostic nutrition index, total protein and chemotherapy cycle were correlated with the prognosis of PESCC (P<0.05), among which total protein and chemotherapy cycle number were independent factors influencing the prognosis. The results of univariate analysis showed that NLR、PLR、SII、CRP were correlated with prognosis, in which SII and CRP were independent prognostic factors. 
   Conclusion   PESCC has a high degree of malignancy and poor prognosis, and there are differences in prognostic factors between LD and ED patients. Total protein value (HR=0.890,95%CI:0.805-0.983,P=0.022) and chemotherapy cycle (HR=0.388,95%CI:0.187-0.807,P=0.011) were independent prognostic factors for OS in LD patients. SII (HR= 1.002,95%CI:1.000-1.004,P=0.007) and CRP(HR=1.065,95%CI: 1.021-1.111,P=0.004) were independent prognostic factors for OS in ED patients.