Evaluation of progression-free status at 24 months as surrogate endpoint for overall survival in HPV-positive oropharyngeal cancer

A retrospective cohort study at Memorial Sloan Kettering Cancer Center (New York, NY) evaluated progression-free status at 24 months (PFS24) as surrogate endpoint for overall survival (OS) in adult patients who received radiotherapy for HPV-positive oropharyngeal cancer (HPV+ OPC). The study included 1245 patients (median age 61 years; IQR 55-68; 87.8% male patients) treated between 2013 and 2022. Median follow-up from the start of radiotherapy was 63.3 months (IQR 40.4-91.3). Five-year overall survival rate was 89.3% (95% CI 87.4-91.2). A total of 1163 patients had follow-up data for PFS24, with 1044 (88.3%) being progression-free. The standardized mortality ratio (SMR) compared to the matched general US population after reaching 24-month PFS status was 1.2 (p=0.090). The 5-year subsequent OS rate of patients who reached 24-months progression-free status was 93.1%, similar to the expected 92.7% in the matched US population. Among patients with disease progression within 24 months, the 5-year subsequent OS rate was 33.5%, versus an expected 5-year OS rate of 91.1% in the matched US general population, with a corresponding SMR of 17.9 (p<0.0001). The authors conclude that PFS24 was a strong prognostic marker for OS at patient level in HPV+ OPC.