Pharyngeal Constrictor Dose-Volume Histogram Metrics and Patient-Reported Dysphagia in Head and Neck Radiotherapy.

Area of Science:

• Oncology
• Radiation Oncology
• Medical Physics

Background:

• Long-term survival in head and neck cancer patients treated with radiotherapy is improving.
• Management of long-term side effects, such as dysphagia, is crucial for patient quality of life.
• Dysphagia is linked to radiation dose delivered to the pharyngeal constrictor muscles.

Purpose of the Study:

• To establish prognostic dose constraints for pharyngeal constrictor muscles.
• To correlate dose-volume parameters with patient-reported dysphagia outcomes.
• To identify optimal dose constraints for reducing late dysphagia.

Main Methods:

• Retrospective analysis of 64 patients (training) and 24 patients (testing) with oropharynx/nasopharynx cancer treated with chemoradiotherapy.
• Patient-reported outcomes for late dysphagia assessed using the MD Anderson Dysphagia Inventory at 12 months post-radiotherapy.
• Dose-volume histogram (DVH) metrics for pharyngeal constrictor substructures analyzed using decision tree classification.

Main Results:

• Two key dose constraints identified: pharyngeal constrictor D63% < 55 Gy and superior-middle constrictor V31Gy < 100%, achieving ≥73% accuracy and ≥80% sensitivity.
• Mean pharyngeal constrictor dose <57 Gy also showed promising results with ≥74% accuracy and ≥60% sensitivity.
• These constraints were validated on an independent testing cohort.

Conclusions:

• Mid-dose constraints for pharyngeal constrictor muscles and their substructure combinations are effective in predicting and reducing late dysphagia.
• Implementing these dose constraints in treatment planning can significantly improve patient quality of life.
• This research provides evidence-based guidelines for optimizing radiotherapy planning to minimize swallowing dysfunction.