Comparative Performance of the 7th and 8th Editions of the American Joint Committee on Cancer Staging Manual for Adrenocortical Carcinoma

Abstract

Background: The American Joint Committee on Cancer 8th edition staging manual for adrenocortical carcinoma (ACC) redefines T stage to include large vessel invasion (T4, previously undescribed) and restricts stage IV to those with distant metastases. We evaluated the prognostic power of the 8th edition. Methods: Patients with ACC treated between January 1, 2000, and December 31, 2015, were identified. Overall survival (OS) was compared using Kaplan–Meier and Cox proportional hazard models. Results: Of 290 patients evaluated, the change in T stage nomenclature impacted 13 (4.5%) who were previously categorized as T3; 61 had large vessel involvement but were already T4 based on invasion of adjacent organs. The restriction of stage IV to patients with distant metastases downstaged 41 (14.1%; T4N0M0 or T3–4N1M0) to stage III. In the 7th edition, the hazard ratio (HR) for death was similar between patients with stage II and III disease, with 5-year OS 66.7%, 54.4%, 57.2%, and 14.0% (stages I, II, III, and IV, respectively). In the 8th edition, stages I and II remain unchanged, with 5-year OS for stage III and IV 44.1% and 9.2%, respectively. The c-index for the 7th and 8th editions was similar (83.4 and 82.7, respectively). Conclusions: While 8th edition changes impact a relatively small proportion of ACC patients, they represent progress toward a common staging system that accurately reflects prognosis. In the 8th edition, the inclusion of patients with T4 tumors or nodal disease as stage III rather than IV results in improved stratification between stages II and III.