Dose and Volume De-Escalation for Human Papillomavirus-Positive Oropharyngeal Cancer is Associated with Favorable Post-Treatment Functional Outcomes.

PURPOSE: To report functional outcomes for patients with HPV-positive oropharyngeal cancer treated on a phase II protocol of risk- and induction chemotherapy response-adapted dose and volume de-escalated radiation (RT)/chemoradiation (CRT). MATERIALS/METHODS: Patients were stratified as low-risk (LR) or high-risk (HR) according to T/N-stage and smoking history. Induction chemotherapy was followed by radiographic response assessment. LR patients with >/=50% response received 50Gy RT (RT50) whereas LR patients with 30-50% response or HR patients with >/=50% response received 45Gy CRT (CRT45). All other patients received 75Gy CRT (CRT75) with RT limited to the first echelon of uninvolved nodes. Pre- and post-RT/CRT modified barium swallow studies were performed. Percutaneous endoscopic gastrostomy (PEG) tube placement, body mass indices (BMI), and narcotic use were recorded. Statistical comparisons used linear or logistic regression, the Mann-Whitney U test, the chi square test, or Fisher's exact test as appropriate. RESULTS: Twenty-eight LR and 34 HR patients were enrolled, and 49 completed RT50/CRT45 while 11 completed CRT75. PEG-tube dependency at the end of RT/CRT and 3 months post-RT/CRT significantly differed according to risk- and treatment groups (all p /=4, more likely to have Rosenbek's penetration-aspiration scores >/=7, more likely to have developed trismus, and more likely to require narcotics >2 months (all p<0.05). CONCLUSIONS: Induction chemotherapy followed by risk- and response-adapted dose and volume de-escalated RT/CRT is associated with clinically meaningful functional outcomes including (1) improved swallowing function, (2) higher BMI, and (3) shorter narcotic use for patients receiving de-escalation.