The American Joint Committee on Cancer (AJCC) established a standard system for cancer staging based on 3 key components: local tumor extent (T stage), dissemination to the regional lymph nodes (N stage), and metastatic spread to distant sites (M stage), collectively referred to as TNM staging. According to a recent study published in JAMA Surgery, the recently released eighth edition of the AJCC TNM staging provides a more equal distribution among stages and modestly increases prognostic accuracy, compared to the previous edition.

The study included 1525 patients, median age 66, from 5 tertiary centers in Europe and in the United States from 2000 to 2015, who underwent pancreatoduodenectomy for nonmetastatic pancreatic ductal adenocarcinoma. The patients were retrospectively staged based on the criteria of either the seventh or the eight edition of TNM staging.

Using the eight edition, 774 patients were recategorized to a different stage; 183 patients to a lower stage and 591 patients to a higher stage. Under the seventh edition, the distribution of stages were: 41 patients in IA, 42 in IB, 200 in IIA, 1229 in IIB, and 12 in III. The distribution of patients under the eight edition was more even: 118 patients in IA, 144 in IB, 22 in IIA, 643 in IIB, and 598 in III. The 5-year survival rate changed from 38.2% in stage IA, 34.7% in IB, 35.3% in IIA, 16.5% in IIB, and 0% in stage III, per the seventh edition, to 39.2% in stage IA, 33.9% in IB, 27.6% in IIA, 21.0% in IIB, and 10.8% in stage III, using the eight edition. 

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The T stage for both editions was not associated with prognostication of survival. In contrast, the eight edition added a subdivision of the N stage which highly improved its prognostic power. The concordance statistic of the eighth edition was 0.57 compared with 0.55 for the seventh edition. 

Reference

van Roessel S, Kasumova GG, Verheij J, et al.International Validation of the Eighth Edition of the American Joint Committee on Cancer (AJCC) TNM Staging System in Patients With Resected Pancreatic Cancer[published online October 3, 2018]. JAMA Surg. doi: 10.1001/jamasurg.2018.3617