Concurrent immunoradiation for HPV-associated oropharyngeal squamous cell carcinoma

Current trials for HPV-associated oropharyngeal SCCs (OP-SCCs) are evaluating treatment de-escalation including use of concurrent immunotherapy with radiation therapy (I-RT). Given limited prospective data following I-RT, we aimed to examine this question utilizing the National Cancer Data Base (NCDB).

The NCDB was queried for patients with HPV-associated OP-SCCs eligible for current de-escalation studies with AJCC 7th edition T1-T2/N1-N2b and T3/N0-N2b disease. Patients were stratified into I-RT, concurrent chemoradiation (C-RT), and radiation therapy alone (RT) arms. Kaplan-Meier analysis was utilized to compare overall survival (OS) between treatment arms followed by a Cox multivariate (MVA) proportional hazards model controlling for tumor and patient characteristics and propensity-score analyses with inverse probability treatment weighting (IPTW).

We identified 4768 patients; 313 received I-RT, 3660 patients received C-RT, and 795 received RT. Median age was 62 years (range 27-90) with a median Charlson-Deyo co-morbidity score of 0 (range: 0-3). The vast majority were cN1-N2a (88.8%) and 26.5% were cT3. On MVA, inferior 3-year and 8-year OS was noted following I-RT (81.6% and 70.5%) vs. C-RT (90.6% and 79.4%) (HR = 1.69 (95% CI: 1.29-2.21); p < 0.0001) with no significant difference vs. RT (88.1% and 75.8%) (HR = 1.07; p = 0.80). This was also maintained on IPTW-analysis (HR = 1.62 (95% CI: 1.23-2.15); p = 0.001).

I-RT was associated with significantly poorer OS vs. C-RT with no benefit compared to RT for HPV-associated OP-SCCs. I-RT is not recommended outside of currently accruing clinical trials.