Mandibular Radiation Dose Modifies the Association Between Post-Chemoradiotherapy Dental Extraction Timing and...

Area of Science:

• Oncology
• Radiation Oncology
• Oral and Maxillofacial Surgery

Background:

• Locally advanced nasopharyngeal carcinoma (LA-NPC) patients treated with definitive concurrent chemoradiotherapy (CCRT) face risks of osteoradionecrosis of the jaw (ORNJ).
• The interplay between post-CCRT dental extraction timing and mandibular radiation dose in ORNJ development requires further elucidation.

Purpose of the Study:

• To investigate if mandibular radiation exposure modifies the association between post-CCRT dental extraction timing and ORNJ risk in LA-NPC patients.
• To identify predictors of ORNJ in patients undergoing post-CCRT dental extractions.

Main Methods:

• Retrospective analysis of 247 LA-NPC patients who underwent post-CCRT dental extractions.
• Quantification of mandibular radiation exposure using EQD2 and assessment of extraction timing.
• Multivariable logistic regression and ROC analyses to evaluate ORNJ risk factors and interactions.

Main Results:

• Mandibular EQD2 (OR 2.10 per 5 Gy) and extraction timing showed a significant interaction (OR 1.07) influencing ORNJ risk.
• EQD2 (AUC 0.885) was a strong predictor, with higher doses (≥46.5 Gy) significantly increasing ORNJ incidence with delayed extraction (31.1%).
• Number of extracted teeth (OR 1.16) and hemoglobin level (OR 0.62) were independent predictors.

Conclusions:

• The impact of post-CCRT dental extraction timing on ORNJ risk is significantly modified by the mandibular radiation dose.
• Mandibular radiation exposure must be considered alongside extraction timing for accurate ORNJ risk assessment.
• Optimizing extraction timing in relation to radiation dose is crucial for preventing ORNJ in NPC survivors.