Comparative Performance of the 7th and 8th Editions of the American Joint Committee on Cancer Staging Systems for Soft Tissue Sarcoma of the Trunk and Extremities

Background: The 8th edition American Joint Committee on Cancer (AJCC) staging for soft tissue sarcomas of the trunk/extremities divides T stage into four categories and upstages nodal disease to stage IV. We used the National Cancer Database (NCDB) to evaluate the prognostic power of the new system. Methods: A total of 26,144 patients were identified from the NCDB from 2004 to 2013. Overall survival (OS) was compared using Kaplan–Meier and Cox proportional hazard models. Results: Including T3 (10 cm > × >15 cm) and T4 (> 15 cm) categories resulted in an increased number of patients classified as stage III (5120 as IIIA [19.6%] and 4280 as IIIB [16.4%], vs. 7882 [30.1%] previously), and there was a small increase in the number of patients classified as stage IV (2776 [10.6%], vs. 2565 [9.8%] previously). In the 7th edition, the hazard ratio (HR) for death increases with stage, with large incremental increases between stages II–III and III–IV. In the 8th edition, the HR for death demonstrates smaller incremental increases between each stage. Five-year OS for 7th edition T1 and T2 patients was 78.8 and 58.8% (p < 0.01), respectively, versus 62.6, 53.5, and 56.1% for T2, T3, and T4 patients, respectively, in the 8th edition (p < 0.01). Patients with isolated nodal disease (n = 211) had a better 5-year OS than those with distant metastases (33.1% vs. 12.4%, p < 0.001). Conclusions: The AJCC 8th edition uses T stage to more accurately stratify OS in patients with large, high-grade tumors (T3/4) compared with those patients with T2 tumors, which facilitates risk assessment. The distinction between T3 and T4 may not be clinically significant. Patients with metastatic nodal disease have a survival outcome intermediate to those with stages III and IV disease.