Comparison of the 11th Japanese classification and the AJCC 7th and 8th staging systems in esophageal squamous cell carcinoma patients

Background: Although the American Joint Committee on Cancer (AJCC) staging system has been used worldwide for esophageal squamous cell carcinoma (ESCC), another staging system has been proposed by Japanese surgeons. The two systems have different lymph node maps, N staging, and stage grouping. This retrospective study compared the predictive ability of these two staging systems for survival. Methods: We retrospectively reviewed records for 143 patients who underwent esophagectomy and mediastinal lymphadenectomy for ESCC from January 2006 to July 2015. Patients were staged by 7th, 8th AJCC stage and 11th Japanese classification. The concordance indexes (C-indexes) of these staging systems were compared. Results: Mean age was 63.14 +/- 8.10 years with 131 (91.6%) men. Median follow-up was 47.73 (6.27-134.40) months. All patients received R0 resection. Recurrences developed in 30 (20.9%) patients. Both AJCC N staging and Japanese N staging well predicted disease-free survival (DFS) (P<0.001). Stage groupings of AJCC 7th and 8th and Japanese 11th classification also predicted DFS well (P<0.001). The c-index was 0.755 (95% CI, 0.650-0.860) for AJCC N staging and 0.734 (0.634-0.835) for Japanese N staging (P=0.11). The c-index was 0.813 (0.732-0.896) for AJCC 7th stage grouping, 0.805 (0.726-0.885) for AJCC 8th, and 0.837 (0.766-0.908) for Japanese stage grouping. The C-index for the Japanese stage grouping was slightly higher than for AJCC, but differences were not significant. Conclusions: Both N staging and stage grouping for the 11th Japanese classification and 7th and 8th AJCC staging for ESCC showed similar predictive power for DFS. Both systems could be applied in clinical situations.