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

<bold>Purpose: </bold>To report functional outcomes for patients with human papillomavirus-positive oropharyngeal cancer treated on a phase 2 protocol of risk- and induction chemotherapy response-adapted dose and volume de-escalated radiation therapy (RT)/chemoradiation (CRT).<bold>Methods and Materials: </bold>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 50 Gy RT (RT50), whereas LR patients with 30% to 50% response or HR patients with ≥50% response received 45 Gy CRT (CRT45). All other patients received 75 Gy 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 index (BMI), and narcotic use were recorded. Statistical comparisons used linear or logistic regression, the Mann-Whitney U test, the χ2 test, or Fisher's exact test as appropriate.<bold>Results: </bold>Twenty-eight LR and 34 HR patients were enrolled; 49 completed RT50/CRT45 and 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 < .05). Treatment intensity was independently associated with 3-month PEG status while adjusting for risk group (P = .002). The CRT75 group had a median -8.42% change from baseline BMI at 1 year post-RT/CRT versus -2.54% for the RT50/CRT45 group (P = .01). At the end of RT/CRT, CRT75 patients were less likely to tolerate a normal diet, more likely to have swallowing performance status scale scores ≥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 < .05).<bold>Conclusions: </bold>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. [ABSTRACT FROM AUTHOR]