Prospective pilot study evaluating dental side effects of radiotherapy on subjects treated for head and neck cancer: StomRay Study

Background : Head and Neck Squamous Cell Carcinoma (HNSCC) remains a significant global cause of mortality, with late-stage diagnoses contributing to unfavorable prognosis ¹ . Radiotherapy (RT) is crucial in HNSCC treatment but poses risks, including osteoradionecrosis of the jaw (ORNJ) and dental issues post-irradiation ² . Pre-RT dental restoration is recommended, yet some patients undergo unnecessary tooth removal, impacting post-treatment options like dental implants or bridges ³ . To address this, a predictive model for dental avulsions pre-RT is being developed. It aims to identify low-risk areas (<40 Gy) for ORNJ based on tumor location and clinical tumor classification. Three risk groups are considered based on radiation doses: high risk (>50 Gy), low risk (<40 Gy), and an intermediate group (40-50 Gy). A color-coded system categorizes irradiated areas on the dental arch, simplifying assessments for molar, premolar, and incisor groups. This approach aimed to balance the need for dental interventions before RT, optimizing patient care and post-treatment quality of life. Methods: Patients diagnosed with HNSCC scheduled for RT undergo initial assessment by a stomatologist for a comprehensive dental examination prior to treatment. As part of our protocol, a dental decalcification and splint placement are conducted before the onset of RT. According to our predictive model, teeth expected to receive over 40 Gy, impacting long-term survival, are scheduled for extraction at least two weeks before RT begins. After treatment, patients undergo regular dental evaluations every six months for 36 months to detect and address potential dental issues. Additionally, patients' quality of life was assessed by three different questionnaires, both during and post-RT. The primary goal of our study is to model the risk of dental complications, particularly the likelihood of fractures and dental caries, using the concept of normal tissue complication probability (NTCP). Secondary objectives involved validating our predictive dose model for RT based on tumor location and TNM stage. We aimed to integrate our predictive dose model with dental NTCP to personalize decisions regarding tooth extraction before RT. Moreover, we investigated the impact of partial or total tooth loss and RT on the patient's quality of life. Discussion: Our study is based on the importance of preserving oral health, particularly dental structures, in survivors of HNSCC to enhance their quality of life post-treatment. It highlights the benefits of a conservative approach to dental interventions, especially for HPV-positive oropharyngeal carcinoma patients, aiming to minimize unnecessary procedures and tailor treatments based on individual risk factors. It also emphasizes the significance of identifying teeth at minimal risk of radiation exposure to prevent complications such as osteonecrosis. Additionally, it outlines ongoing research efforts to develop a predictive dose model for guiding dental interventions, aiming to safeguard dental health and overall well-being in HNSCC survivors. Trial registration : ClinicalTrials.gov NCT04452032, study protocol version 1.1_11/08/2020. Registered 25/06/2020