Comparison and validation of the Japanese classification 12th edition and American joint committee on cancer 8th edition on intrathoracic esophageal squamous cell carcinoma.

Background: The American Joint Committee on Cancer (AJCC) 8th edition and Japanese classification 12th edition can be applied for esophageal cancer staging. This retrospective study aimed to compare these two staging systems in patients with surgically treated esophageal squamous cell carcinoma (ESCC).

Methods: We retrospectively reviewed 2,853 patients who underwent esophagectomy and lymphadenectomy from 1994 to 2020. Patients were divided into the upfront (n = 2156) and neoadjuvant (n = 697) groups.

Results: The mean age of the patients was 63.5 ± 8.2 years with a median follow-up of 7.6 years. Comparing both staging systems showed that patients were more likely to be staged lower by the Japanese classification. Survival curves for overall survival (OS) and disease-free survival in the upfront group were well separated in the two staging systems (p < 0.01), and the HR for survival significantly increased as the stage increased. In the neoadjuvant group, there were crossovers of survival curves between stages II and III in the AJCC, and crossovers between stages I and II, and stages III and IV in the Japanese classification. The HR for OS demonstrated less statistical differences in the neoadjuvant group.

Conclusion: The AJCC 8th edition and Japanese classification 12th edition predicted survival well for patients received the upfront surgery, whereas both showed crossovers of survival curves for patients undergoing neoadjuvant therapy. More accurate staging systems for patients with ESCC who received neoadjuvant therapy and surgery are needed.