The effectiveness of the 8th American Joint Committee on Cancer TNM classification in the prognosis evaluation of gastric cancer patients: A comparative study between the 7th and 8th editions.

Background: The 8th edition of the AJCC TNM staging system for gastric cancer was released in 2016 and included major revisions, especially of stage III.

Patients And Methods: Data from 3281 patients with GC who underwent R0 resection between December 2006 and November 2014 were reviewed. Of them, 1579 patients with stage III according to the seventh edition were analyzed and the 7th and 8th TNM classifications were compared.

Results: The most important tumor stages change observed in stage III GC. For stage III patients, the median number of lymph nodes (LNs) resected in stage III patients was 33 (range 5-112), and the optimal cut-off value for the number of LNs resected was 30. Although the 7th edition classification had higher c-index, linear trend and likelihood ratio χ scores, and smaller AIC values compared with those for the 8th edition, which represented the optimum prognostic stratification, however, the differences between 7th and 8th edition seems to be not statistically significant, and AIC demonstrates similar trend as well. Further subgroup analysis found that the 8th staging system generated the marginally better prognostic stratification only when LNs removed ≥30.

Conclusion: The 8th TNM classification may provide better accuracy than 7th edition in predicting the prognosis of stage III GC after R0 resection with LNs harvested ≥30. However, further research in an external validation setting is warranted.