Evaluation of the prognostic value of the new AJCC 8th edition staging system for patients with pancreatic adenocarcinoma; a need to subclassify stage III?

Background: There have been several proposed changes for the 8th edition of the American Joint Commission on Cancer (AJCC) for pancreatic adenocarcinoma. The aim of this study was to evaluate the prognostic value of the new staging system for patients with pancreatic adenocarcinoma, especially in stage III patients. Methods: We analysed the data of patients newly diagnosed with pancreatic adenocarcinoma between 2008 and 2016 at our hospital. Patients were staged according to 7th edition AJCC criteria, as well as the new 8th edition staging system. The pathologic stage was used in the surgical cases, and the clinical stage, determined by radiographic findings, was used in the unresectable cases. Results: Five hundred two patients were identified who met the inclusion criteria. In node-negative patients, there were no significant differences in survival among T 1, 2 and 3 groups according to the 8th edition. The survival rates of patients with N1 (1–3 positive nodes) and N2 (≥4 positive nodes) disease, according to 8th edition, were significantly different (p < 0.001). Although N2 and T4 patients are both stage III according to the new staging system, N2 patients had a better survival rate than T4 patients (p = 0.038). The new staging system stratifies patients more evenly across stages without sacrificing the prognostic accuracy. Conclusions: The AJCC 8th edition has some advantages over the previous version. However, patients with N2 and T4, who have been integrated into stage III, showed different treatment modalities and prognoses, and we proposed dividing stage III into IIIA (T1-3N2M0) and IIIB (T4N_anyM0).