Dosimetric analysis of hearing loss after cranial radiation therapy in children: A single-institution study from the French national registry PediaRT.

PURPOSE: To identify dosimetric predictive factors of sensorineural hearing loss (SNHL) in children after cranial radiation therapy (RT) in a single institution using dosimetric data from the French National Registry PediaRT. METHODS AND MATERIALS: Complete audiological follow-up data were available for 44 children treated with cranial RT between 2014 and 2021 at our institution. The median age at the time of RT initiation was 9 years (range: 2-17 years). No children presented with hearing loss prior to treatment. SNHL was defined as a Chang ototoxicity grade ≥ 1a or higher. RESULTS: Median audiometric follow-up duration was 51 months. Seven children (16 %) developed SNHL with a median time to occurrence of 33 months (range, 18-46 months). The estimated SNHL cumulative rate at 2 years post-RT was 4,5% ± 3,1% and at 5 years was 21 % ± 7.2 %. Multiple Cox regression models showed that the association of the age at radiotherapy and the dosimetric values to the inner ear canal and cochlea were the most significant predictive factors of SNHL occurrence. No child who received less than 35 Gy on average to both cochleae (n = 26) suffered from SNHL, whereas the 5-year SNHL cumulative incidence for the children who received greater than or equal to 35 Gy on average to either cochlea (n = 18) was 51.8 % ± 15.1 %. CONCLUSION: Doses received by the inner ear canal and cochlea, associated with the age at RT initiation, are the main predictive factors for radiation-induced SNHL. A median dose to either cochlea over 35 Gy significantly increases the risk of SNHL and justify close audiometric monitoring to detect and equip hearing loss at an early stage.

Adjuvant pulse-dose-rate brachytherapy for oral cavity and oropharynx carcinoma: Outcome and toxicity assessment of 66 patients.

Purpose: Brachytherapy (BT) is a validated radiation technique for treatment of early stage tumors of oral cavity and oropharynx. This study aimed to analyze the results of our institute's patients after replacing low-dose-rate (LDR) with pulse-dose-rate (PDR) brachytherapy. Material and methods: We retrospectively collected data from all patients treated between 2009 and 2020 for squamous cell carcinoma (floor of the mouth, tongue, and oropharynx) using adjuvant interstitial BT with or without external RT. Primary outcome was local control. Secondary outcomes were regional control rate and toxicity. Statistical analysis of local and regional recurrences were described using Kaplan-Meier method. Prognostic value of each factor for recurrence or toxicity was evaluated with bivariate Fine-Gray model. Results: Data from 66 patients were analyzed. Local and regional recurrences were reported in 11% and 20% of the patients, respectively. No significant factors were identified in the present study. Grade 2 and 3 acute mucositis were reported in 21% of patients, and were more frequent in the BT only group. Almost half (47%) of the patients described acute pain following BT, and 26% required stage 2 or 3 analgesics. Trophic disorders were observed in 16 patients. Five patients presented with soft tissue necrosis (STN) and required medical treatment, of whom one subsequently required hyperbaric oxygen therapy. No predictive factors were identified for STN risk. Two patients developed osteoradionecrosis. Conclusions: Oral and oropharyngeal PDR-BT as adjuvant treatment is safe and effective for well-defined indications.

Dosimetric predictive factors for facial nerve paralysis after cyberknife® stereotactic radiotherapy for vestibular schwannomas: A single institution experience of 88 patients.

PURPOSE: To identify dosimetric predictive factors of facial nerve paralysis for patients with vestibular schwannomas (VS) treated in a single institution with Cyberknife® (CK) hypofractionated stereotactic radiotherapy (SRT). METHODS AND MATERIALS: Eighty-eight patients were treated from 2010 to 2020. Different treatment schedules were used over that period, some prescribed to the 80% isodose line (4 × 5 Gy, 3 × 7 Gy, 3 × 8 Gy and 5 × 5 Gy) and one to the 70% isodose line (3 × 7.7 Gy). Local control tumor and facial nerve toxicity were recorded, as well as various dosimetric indicators. RESULTS: Median follow-up 37 months (range, 7-96). Of the 88 stereotactic treatments, 20 patients (23%) developed objectively diagnosed radiation-induced facial nerve paralysis. The 2-year and 5-year local tumor control were respectively 95% and 88%, and the overall 2-year facial nerve preservation was 76%. Prescriptions with a maximum dose point (Dmax) of 33 Gy were at a substantially higher risk of facial paralysis than prescriptions with a Dmax less than or equal to 30 Gy (HR = 4.51, 95% CI = [1.04;19.6], p = 0.045). The 2-years cumulative incidences of facial paralysis were 32% [20%;44%] in the case of a 33 Gy Dmax, against 7% [1%;21%] otherwise. We identified four significative dosimetric predictive factors for radiation-induced facial nerve dysfunction: a GTV minimal dose over 22 Gy (EQD2 = 45.5 Gy, p = 0.019), a GTV mean dose over 29 Gy (EQD2 = 73.5 Gy, HR = 2.84, 95% CI = [1.10;7.36], p = 0.024), a PTV mean dose over 27 Gy (EQD2 = 64.8 Gy, HR = 10.52, 95% CI = [1.39;79.76], p = 0.002) and a PTV maximal dose of 32 Gy (EQD2 = 87.5 Gy,HR = 5.09, 95% CI = [1.17;22.15], p = 0.013). CONCLUSION: We identified four dosimetric predictive factors for post-treatment facial paralysis. Increasing the doses of hypofractionated stereotactic radiotherapy for vestibular schwannomas leads to higher facial nerve toxicity and may lead to lower local control rates than other published series. Our three-hypofractionated regimens may have also played a role in these results.

Renal Metastases from a Nasal Cavity Mixed Squamous Cell and Adenoid Cystic Carcinoma: A Case Report.

BACKGROUND Adenoid cystic carcinoma (ACC) is a very rare tumor with a high risk of loco-regional recurrence and potential distant metastases. Until now, only a few cases of renal metastases from ACC have been reported in the literature. CASE REPORT A 64-year-old, Caucasian, non-smoker female, 8 months after being treated by radio-chemotherapy for a squamous cell nasal cavity tumor, presented two renal lesions associated with lung and vertebral metastases. Histology was consisted with a metastasis from an ACC. The histological revision of the primary nasal tumor confirmed a squamous cells carcinoma with an adenoid cystic component that metastasized to the kidney. Renal lesions appeared hypometabolic at the ¹8F-fluorodeoxyglucose (¹8F-FDG) PET scan mimicking a primary renal tumor. The patient underwent a systemic, palliative chemotherapy by a weekly carboplatin/paclitaxel/cetuximab regimen that was well tolerated and allowed a lasting tumor control. CONCLUSIONS The particularity of this case relies on the rarity of renal metastasis from ACC, its difficult diagnosis, and the complexity of its management, as no standard chemotherapy has been validated for metastatic ACC, yet. In our case, a weekly carboplatin/paclitaxel/cetuximab regimen was administered leading to a durable tumor stabilization with an excellent patient's quality of life.