Tumor size classification of the 8^th edition of TNM staging system is superior to that of the 7^th edition in predicting the survival outcome of pancreatic cancer patients after radical resection and adjuvant chemotherapy

The 8^th edition of TNM staging system has been released and it incorporates many changes to the T and N classifications for pancreatic cancer. Comparative study between the 7^th and 8^th edition of TNM staging system from Asian population has not been reported yet. This study aimed to compare the 7^th and 8^th edition of staging system for pancreatic cancer by using a cohort of pancreatic cancer patients from China after R0 pancreaticoduodenectomy and adjuvant chemotherapy. The results showed according to the pT classification of 7^th edition, pT3 was predominant (87.25%), however, the new edition led to a more equal distribution of pT classification. pT1, pT2 and pT3 was 27.45%, 56.86% and 15.69%, respectively. According to the new pN classification, 18.63% of the patients were pN2. The pT classification in the 8^th edition was significantly superior to that in the 7^th edition at stratifying patients by overall survival. The pN classification in the 8^th edition failed to show an advantage over the 7^th edition in stratifying patients by overall survival. Therefore, the new pT classification, but not the new pN classification, showed a significant advantage over the previous edition at predicting the overall survival of pancreatic cancer patients.