Date Approved
8-11-2025
Graduate Degree Type
Project
Degree Name
Medical Dosimetry (M.S.)
Degree Program
Allied Health Sciences
First Advisor
Addah Riebschleger
Academic Year
2024/2025
Abstract
Abstract
Purpose: Human papillomavirus–positive (HPV+) head and neck squamous cell carcinoma (HNSCC) exhibits a favorable prognosis and high radiosensitivity, prompting interest in radiotherapy de-escalation to reduce treatment-related morbidity without compromising tumor control. This study evaluated the dosimetric and short-term clinical impact of reducing the prescription dose from 70 Gy to 50 Gy, focusing on sparing organs at risk (OARs) linked to long-term functional outcomes.
Methods: Ten patients with HPV+ HNSCC previously treated with definitive 50 Gy volumetric-modulated arc therapy (VMAT) were retrospectively replanned to 70 Gy using identical target volumes, coverage goals, and optimization strategies. Mean doses to the oral cavity, bilateral parotid glands, and bilateral submandibular glands were extracted from both plans and compared using the non-parametric Sign Test. Effect sizes quantified the magnitude of differences. Limited toxicity data were reviewed for the 50 Gy cohort, focusing on percutaneous endoscopic gastrostomy (PEG) tube placement and acute Grade ≥2 swallowing or salivary toxicity.
Results: All OARs demonstrated statistically significant and clinically meaningful mean dose reductions with the 50 Gy plans. The largest differences were observed in the submandibular glands (median reductions: 1858.35 cGy left, 1836.55 cGy right), followed by the oral cavity (1094.5 cGy) and parotid glands (637.7–754.8 cGy). Effect sizes were large to very large for all structures. No PEG tubes were placed, and no acute Grade ≥2 dysphagia was reported in the 50 Gy group.
Conclusion: Dose de-escalation from 70 Gy to 50 Gy in HPV+ HNSCC significantly reduces radiation exposure to critical salivary and oral cavity structures while maintaining target coverage. Even moderate improvements in dryness, taste, and swallowing may enhance daily functioning, emotional well-being, and social engagement. These findings support the feasibility of evidence-based de-intensification strategies and highlight the need for larger, prospective trials incorporating long-term toxicity and quality-of-life metrics.
ScholarWorks Citation
Kaysen, Rebekah, "Exploring the Impact of De-escalated Dosage on OARs for HPV+ HNSCC and Their Associated Toxicities" (2025). Culminating Experience Projects. 632.
https://scholarworks.gvsu.edu/gradprojects/632
