Background: In the seventh edition of the AJCC TNM system for esophageal cancer, modifications have been made with regard to definition of nodal status; histological grade and tumor location are also added in overall staging. The aim of this study is to evaluate the prognostic value of this new system.
Patients and methods: From 1995 to 2009, 200 patients with squamous cell carcinoma who underwent esophagectomy with curative intent (R0 resection) without neoadjuvant or postoperative treatment were studied.
Results: For nodal staging, survival difference was found between pN0 and pN + groups of the sixth edition. If nodal status was recoded according to the seventh edition, survival distinction was found between different groups except between pN1 (1-2 nodes) and pN2 (3-6 nodes) (p = 0.47). When pN1 and pN2 were pooled together (pN1+2), survival distinction between pN0 and pN1+2 (p = 0.003), and pN1+2 and pN3 (7 or more nodes) (p < 0.001) were identified. For overall staging, stage distributions were stage I = 17, stage II = 80, stage III = 89, and stage IV = 14 according to the sixth edition. The respective numbers were stage I = 20, stage II = 69, stage III = 111, using the seventh edition. Using the sixth edition, survival differences between stages were distinct except between stage III and stage IV (p = 0.38). In the seventh edition, survival differences were found among all stages: between stage I and II (p = 0.01) and between stage II and III (p < 0.001). On multivariate analysis, pT and pN were two independent prognostic factors for both editions. In the seventh edition, histological grade and tumor location were not statistically significant prognostic factors.
Conclusions: The new staging system provides better survival distinction between stages. pT and pN were independent prognostic factors whereas histological grade and tumor location were not. Nodal metastases may be better reassigned to three groups: pN0, pN1 (1-6), and pN2 (7 or more).