Latest AJCC TNM Staging System for Resected Pancreatic Cancer

The most recent edition of the American Joint Committee on Cancer (AJCC) TNM staging system for pancreatic cancer includes a more equal distribution among disease stages and increased prognostic accuracy compared with the previous version, results from a validation study reveal (JAMA Surg. 2018 Oct 3. Epub ahead of print).

Seeking to validate the eighth edition of the AJCC TNM staging system for pancreatic cancer, Stijn van Roessel, MD, Department of Surgery, Cancer Center Amsterdam, Amsterdam UMC, University of Amsterdam, the Netherlands, and colleagues conducted an international study on 1525 patents with resected pancreatic ductal adenocarcinoma from 2000 to 2015.

“This study represents the first international validation of the eighth edition of the AJCC TNM staging system in a cohort from 4 different countries across Europe as well as the United States,” Dr Roessel and colleagues said. Patients (median age, 66 years; 802 men) were eligible for participation if they underwent pancreatoduodenectomy for nonmetastatic disease.

The investigators staged patients retrospectively in accordance with the seventh and eighth editions of the TNM staging system, and used Kaplan-Meier and multivariate Cox proportional hazards analyses and concordance statistics to examine prognostic accuracy regarding survival rates. Data were analyzed between December 2017 and April 2018.

Among patients staged via the seventh edition of the AJCC TNM staging system, 41 (2.7%) had stage IA disease, 42 (2.8%) had stage IB, 200 (13.1%) had stage IIA, 1229 (80.6%) had stage IIB, and 12 (0.8%) had stage III. With the eight edition of the staging system, these values changed; 118 patients (7.7%) had stage IA disease, 144 (9.4%) had stage IB, 22 (1.4%) had stage IIA, 643 (42.2%) had stage IIB, and 598 (39.2%) had stage III.

A total of 774 (50.8%) patients migrated to a different disease stage with the eighth edition—183 (12.0%) were reclassified to a lower stage and 591 (38.8%) to a higher stage. Among all patients, the median overall survival was 24.4 months (95% confidence interval [CI], 23.4-26.2 months).

According to the Kaplan-Meier analysis, and with the seventh versus eighth editions of the staging system, 5-year survival rates changed from 38.2% for patients with stage IA disease, 34.7% with stage IB, 35.3% with stage IIA, 16.5% with stage IIB, and 0% with stage III to 39.2% for patients with stage IA disease, 33.9% with stage IB, 27.6% with stage IIA, 21.0% with stage IIB, and 10.8% with stage III.

Of note, T stage was not associated with prognosis of survival in node-negative patients with either staging system edition.

“The results of this study are generalizable and clinically applicable, with an international cohort representing heterogeneity mainly in patients but also in pathological procedures, including different slicing techniques,” Dr Roessel and colleagues said.

“Overall, increased prognostic accuracy was found for the eighth edition of the AJCC TNM staging system compared with the seventh edition,” they concluded.—Hina Khaliq