The Applicability of the AJCC TNM Staging 8th Edition to Esophageal Small-Cell Carcinoma: A Multicenter Retrospective Trial from China

Abstract

Small cell carcinoma of the esophagus (SCCE) is a rare type of esophageal cancer, the incidence of it is only 0.1% to 2.4% in all cases of esophageal cancer. However, the optimal disease staging system has not yet been defined. To comprehensively explore the impact of AJCC TNM Staging 8th edition on survival outcome of SCCE. From January 2007 to December 2020, 909 patients with SCCE who had completed TNM staging from 14 cancer centers in China were retrospectively examined. Univariate survival rate analyses were estimated using the Kaplan and Meier method, with comparisons made between groups by the log-rank test. All statistical analyses were conducted using SPSS 25 statistical software. Statistical significance was assumed for a two-tailed p value less than 0.05. TNM stage also was a statistically significant prognostic factor for OS and PFS in SCCE(p<0.001). Increasing clinical T category using the AJCC8 TNM staging system resulted in progressively poorer survival in patients who did not have metastatic (M0) involvement(p<0.01). However, the results of pairwise comparisons showed no significant differences in survival between patients with adjacent phases except for those between T3 versus T2 (p<0.0001). N staging also showed significant influence on OS, and with significant difference between successive stages (p<0.05) except that between the survival rates of N1 and N2 cases (p = 0.00758). Similar to t category, increasing M category was associated with progressively worse survival. The T and N staging confirmed significant influence on PFS in the SCCE patients (p<0.001). AJCC TNM Staging 8th edition criteria for SCCE patients has a high prognostic impact. Therefore, it is applied to clinical practice and future therapeutic trials.