(0723) Role of Pretreatment PET/CT on Oncologic Outcomes: A Secondary Analysis of a Randomized Controlled Trial

Introduction: A phase III randomized clinical trial, RTOG 0522, examining combination triple therapy (cetuximab-cisplatin-RT) for locally advanced head and neck cancer did not demonstrate improvement in survival outcomes. However, the heterogeneity of the study cohort could have been influenced by pre-treatment imaging as patients with pre-treatment PET/CT scans may have been staged earlier, lending to differing oncologic outcomes. The purpose of this study was to perform a secondary analysis of the RTOG 0522 trial to evaluate whether pre-treatment PET/CT imaging influences survival outcomes.

Methods: Of 940 patients enrolled in the trial, 891 participant data meeting inclusion criteria (participants at least 18 years of age with untreated stage III/IV SCC of the oropharynx, hypopharynx, larynx, Zubrod performance status 0 to 1, and appropriate bone marrow, hepatic, and renal function) were retrospectively analyzed. Outcomes of interest were overall survival, locoregional failure, distant metastasis, and progression-free survival. The Kaplan-Meier method, cumulative incidence method, and hazard ratios using cox proportional hazard models and competing risks regression were performed. Sub-group analysis for patients with oropharyngeal cancer stratified based off p16 status was performed.

Results: Patients who underwent a PET/CT had improved OS compared to patients who did not receive a PET/CT (HR 0.77, 95% CI 0.6-0.98, p 0.037). There was no statistically significant difference in overall survival for patients with oropharyngeal cancer stratified by p16 status. There was no statistically significant difference in progression free survival, locoregional failure, or distant metastasis in the overall population (n = 891) or in patients with oropharyngeal cancer stratified based on p16 status (n = 625).

Conclusions: Patients with advanced head and neck cancer who had a pre-treatment PET-CT appear to have improved overall survival compared to patients without a pre-treatment PET/CT.