Evaluation of the AJCC 7th, ICON-S, and HPV-Path Staging Systems for Surgically Managed HPV/p16+ve Oropharyngeal Squamous Cell Carcinoma Patients

Abstract

The differences in the outcome of HPV positive and the HPV negative patients have led to a separate staging system for oropharyngeal squamous cell carcinoma (OPSCC). The changes have been driven by the ICON-S Trial (clinical staging) and the HPV-Path Study (Pathological System) both of which have been incorporated in the new AJCC 8th edition. The purpose of our study is to evaluate the two staging systems along with the previously used AJCC 7th edition, in terms of predicting outcomes, in patients undergoing surgery as the initial treatment at one institute. A retrospective review of IRB-approved patient database at one institute, from 1985 to 2015, was used to identify patients with HPV/p16+ve OPSCC. Patients that had received any form of neoadjuvant therapy, had HPV negative or unknown status, or with metastatic disease at presentation were excluded from the study. The clinicopathological data were utilized to categorize patients based on the AJCC 7th edition, ICON-S, and HPV-Path Staging systems. The survival data were analyzed using Kaplan-Meier methods. The Breslow test was used for univariate analysis to evaluate staging systems. A total of 218 patients were found eligible for the study. The baseline characteristics of the study cohort were similar to the ICON-S trial and the HPV-Path study. The AJCC 7th staging system failed to predict outcomes and did not serve as a good model for the survival data. The ICON-S system performed better than the AJCC-7th by the reclassification of the nodal categories, but it failed to show a significant difference in 5-year OS for Stage I and II (P = .192). The HPV-Path system accounting for the number of nodes involved served as the best fit, with a consistent decline in survival across all stages with no overlap (Table 1). The current analysis shows the improvement of both the ICON-S and HPV-Path staging system over the current AJCC 7th edition. It also serves as a strong evidence of better performance of the pathological staging system over the newly adopted clinical staging system in patients with surgery as the initial treatment.Abstract 134; Table 1Evaluation of different staging systems with respect to 5-year OS and 5-year DSSAJCC – 7th editionStaging System5-year OSP Value5-year DSSP ValueStage 133.3%NA0NAStage 286.5%Ref86.5%RefStage 381.7%.24182.8%.446Stage 479.2%.94789.7%1.863ICON-S systemStaging System5-year OSP Value5-year DSSP ValueStage 182.4%Ref89.4%RefStage 276.9%.19279.1%.059Stage 354.5%.00971.4%.621HPV-Path SystemStaging System5-year OSP Value5-year DSSP ValueStage 186.9%Ref93.1%RefStage 267.2%.00275.2%.005Stage 330.0%<.00140.0%.000 Open table in a new tab