Dosimetric parameters predicting radiation-induced oral mucositis in head-and-neck cancers in two intensity-modulated radiation therapy protocols: A retrospective analytical study

Background: In locally advanced head-and-neck cancers (HNCs), definitive chemoradiation therapy has emerged as the treatment of choice due to the benefit of organ preservation. Radiation therapy is known to cause significant acute and late toxicities when it is used at radical doses. Studies have shown that more severe toxicities such as mucositis were observed in patients who received radiation therapy with concurrent chemotherapy. Incidental radiation exposure to buccal mucosa during radiation therapy for HNCs contributed to acute radiation-induced oral mucositis (RIOM). Objective: The objective of the study was to dosimetrically evaluate the dose received by buccal mucosa in patients with HNC patients undergoing sequential intensity-modulated radiotherapy technique (SEQ-IMRT) and simultaneous integrated boost intensity-modulated radiotherapy technique (SIB-IMRT). Materials and Methods: Forty patients with histologically proven squamous cell carcinoma of head and neck excluding nasopharyngeal and oral cavity cancers, who received radical chemoradiation therapy by SEQ-IMRT or SIB-IMRT were retrospectively analyzed. The total prescribed dose to the planning target volume was 70 Gy delivered in 2 Gy daily fractions in SEQ-IMRT and 66 Gy in 30 fractions in SIB-IMRT. All patients received concurrent weekly injection cisplatin (35 mg/m2). Dosimetric parameters of right and left buccal mucosa (V 15 Gy, V 30 Gy, and V 45 Gy) were recorded and correlated with grades of RIOM and weight loss as per CTCAE v5.0. Results: Mucositis and weight loss were accessed from week 1 to 7 in the SEQ-IMRT arm and week 1–6 for SIB-IMRT arm. Grade 3 mucositis was observed among 2 patients (10%) and 3 (15%) patients in the SIB-IMRT and none in SEQ-IMRT arm. Grade 2 Weight loss was observed among 35% of patients in SIB-IMRT arm and 5% patients in SEQ-IMRT arm. Conclusion: This study assessed the occurrence of several RIOM as predictive factor with respect to dose received to buccal mucosa in HNC patients, except nasopharyngeal and oral cavity cancer. Our data demonstrated relationship between V30 Gy of buccal mucosa and oral mucosal toxicity with associated weight loss in patients with HNCs undergoing radical chemoradiation therapy