[Validation of the 8th Edition of the UICC TNM Classification for Stage Ⅲ Gastric Cancer].

Background: The 8th edition of the UICC TNM Classification was released in 2017 and introduced N3a/N3b groupings for gastric cancer. The purpose of this study was to evaluate the validity of the new classification for Stage Ⅲ gastric cancer.

Patients And Methods: Clinical and pathological data on 388 patients who underwent R0 resection from January 1992 to December 2016 in our institution were retrospectively analyzed. The survival in the 7th and 8th edition stage groupings were compared. Differences in survival according to N classification were also examined in the groups with T4a tumor depth.

Results: 1. The 5-year overall survival(OS)probabilities for Stage ⅢA, ⅢB, and ⅢC of 7th edition were 47.6%, 55.0%, and 28.5%(p=0.0003)and the recurrence-free survival(RFS)rates were 81.1%, 79.4%, and 58.7%(p=0.0013), respectively. In contrast, the OS probabilities of the 8th edition were 50.2%, 41.3% and 30.1%(p=0.0009)and the RFS were 81.6%, 70.9% and 50.0%(p=0.0003), respectively. 2. For T4a tumor depth, the OS probabilities of N1, N2, N3a, and N3b were 48.8%, 54.0%, 27.5%, and 25.1%(p=0.0012)and the RFS were 82.7%, 81.2%, 57.0% and 48.7%(p=0.0013), respectively.

Conclusion: The 8th edition of the UICC TNM classification may provide better accuracy than that of the 7th edition in predicting the prognosis of Stage Ⅲ gastric cancer.