Effects of the dose-volume relationship on and risk factors for maxillary osteoradionecrosis after carbon ion radiotherapy

Abstract

BackgroundOsteoradionecrosis (ORN) is a critical complication after carbon ion (C-ion) or photon radiotherapy (RT) for head and neck tumors. However, the risk factors for ORN after C-ion RT remain unclear. Therefore, the present study aimed to investigate the effects of the dose-volume relationship on and risk factors for ORN development after C-ion RT. We, however, focused on the maxillary bone because most tumors treated with C-ion RT were primarily located in the sinonasal cavity.MethodsThe patients enrolled in this study received more than 10% of the prescribed total dose of 57.6 Gy equivalent (GyE) in 16 fractions to their maxilla. All patients were followed up for more than 2 years after C-ion RT. Those with tumor invasion to the maxilla before C-ion RT or local recurrence after the treatment were excluded from the study to accurately evaluate the effects of irradiation on the bone. Sixty-three patients were finally selected. The severity of ORN was assessed according to the Common Terminology Criteria for Adverse Events version 4.0. The correlation between clinical and dosimetric parameters and ORN incidence was retrospectively analyzed.ResultsThe median follow-up period was 79 months. Of the 63 enrolled patients, 26 developed ORN of grade ≥1. Multivariate analysis revealed that the maxilla volume receiving more than 50 GyE (V50) and the presence of teeth within the planning target volume were significant risk factors for ORN. Dose-volume histogram analysis revealed that V10 to V50 parameters were significantly higher in patients with ORN than in those without ORN.ConclusionsV50 and the presence of teeth within the planning target volume were independent risk factors for the development of ORN after C-ion RT using a 16-fraction protocol.

Feasibility of carbon‐ion radiotherapy for oral non‐squamous cell carcinomas

“…Kuhnt et al reported that 6.6% of 775 patients with head and neck cancer developed severe ORN that required extensive surgical intervention after photon RT, with the highest frequency being observed for oral cavity tumors (13.6%) . Similarly, the present study revealed an incidence of 13.5% for grade 3 ORN among patients with oral malignancy who underwent C‐ion RT, which is higher than the incidence from our previous study of head and neck malignancies (4.8%) . Thus, it appears that C‐ion RT and photon RT were associated with similar incidences of grade 3 ORN, despite the fact that the areas of ORN were localized because of the dose‐localization properties of carbon ions …”

“…Thus, it appears that reconstruction using only soft tissue flaps after sequestrectomy may be acceptable for patients who are treated using C‐ion RT. In addition, we have reported that the presence of teeth within the PTV and the volume of the maxillary bone receiving ≥50 Gy (RBE) are independent risk factors for ORN after C‐ion RT . Therefore, to reduce the risk of ORN, we routinely perform preemptive extraction of teeth with poor prognoses that are near the irradiation field.…”

“…Thus, 64 Gy (RBE) might be recommended as the standard prescribed dose for oral non‐SCC, with the exception of cases in which the mandibular bone or the maxillary bone is extensively irradiated, as in palatal malignant melanoma. The volume of jawbone receiving more than 50 Gy (RBE) in 16 fractions was found to be a risk factor of ORN . The technological advancements made in recent years in scanning‐beam and gantry‐based treatment delivery reduce the volume of the jawbone that is exposed to high‐dose irradiation, which may decrease the risk of ORN …”

“…In addition, Koto et al evaluated 260 patients with mucosal melanoma who underwent C‐ion RT and reported 5‐year rates of 72.3% for local control and 44.6% for OS. However, osteoradionecrosis (ORN) remains a major complication of C‐ion RT for head and neck malignancies, with grade ≥3 ORN developing in 4.8% of these cases . The relatively high risk of ORN in this setting is likely related to the proximity of the oral malignancy to the jawbone, relative to other head and neck malignancies.…”

Evaluation of the safety and efficacy of carbon ion radiotherapy for locally advanced adenoid cystic carcinoma of the tongue base

“…In the present study, 2 patients developed grade 3 mandible osteoradionecrosis. We recently reported the risk factors for developing maxillary osteoradionecrosis after C‐ion RT . In the multivariate analysis, a maxillary volume receiving >50 Gy (RBE) and the presence of teeth in the PTV were extracted as independent risk factors.…”