Risk factors for acute toxicities in oral mucosa and salivary glands during volumetric modulated arc therapy planning technique for head and neck cancer

Intoduction: Volumetric modulated arc therapy (VMAT) is a radiotherapy (RT) modality primarily indicated for the treatment of head and neck neoplasms due to its efficiency in preserving organs at risk adjacent to the tumor area, thereby reducing the inherent toxicities of radiotherapy. Despite that, patients still have significant acute side effects, such as oral mucositis, xerostomia, taste alterations and weight loss. These conditions can cause delays and interruption of RT, potentially affecting general treatment and tumor response.

Purpose: To examine the occurrence, timing, and radiation dose associated with acute side effects on the oral cavity in patients who underwent head and neck RT using Volumetric Modulated Arc Therapy (VMAT) technique. It was also investigated whether these side effects affected nutritional status.

Methods: Data on age, gender, tumor type, radiation doses, oral mucositis (OM), dysphagia, xerostomia, taste changes, weight loss and diet from 95 medical records from a single head and neck VMAT service.

Results: Severe OM was found in 45.8% of patients, occurring at a cumulative dose of 37 Gy between the 9th and 15th radiation fractions. Predictive factors for severe OM were ≥65 Gy maximum dose (Dmax) in the oral cavity and concurrent chemotherapy. Severe OM was associated with weight loss during RT. Xerostomia was observed in 86.3% of patients, occurring at 22 Gy cumulative dose and around the 8th radiation fraction. Xerostomia onset was determined by ≥25 Gy mean dose (Dmean) in the parotid gland. Taste changes were reported by 82.1% of patients and were associated with xerostomia and a ≥35 Gy Dmean in the oral cavity.

Conclusion: The frequency of acute side effects on the oral cavity was high in patients treated with VMAT, significantly impacting nutritional status. The radiation dose to the oral mucosa and salivary glands was associated with most of these side effects.

Corresponding author: Marcella Ferreira Gobbi (e-mail: marcellafgobbi@gmail.com).