ESTRO 2023 - Abstract Book

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ESTRO 2023

Although dry eye is not a common radiation-induced complication for NPC RT, we propose the delineation of the LG as an organ at risk in case of closely advanced NPC as well as stricter dose constraints in the absence of radiation-induced dry eye prevention. The results of this study show that these constraints could be reasonable to respect during dosimetric optimization: Dmean ≤ 11 Gy and Dmax ≤ 30Gy.These results should to be confirmed by larger prospective series with clinical assessement.

PO-1196 Submandibular gland transfer to preserve salivary function: a prospective study of 16 HN patients

V. Moiseenko 1 , T. Atwood 1 , C. Coffey 1 , L. Blumenfeld 1 , P. Hua 1 , C. Bojechko 1 , B. Tuma-Marcella 1 , P. Sanghvi 1

1 University of California San Diego, Radiation Medicine and Applied Sciences, La Jolla, USA

Purpose or Objective To investigate if submandibular gland (SMG) transfer in head-and-neck (HN) cancer patients receiving radiotherapy (RT) can lead to sparing salivary flow and salivary function mediated quality of life. Materials and Methods Sixteen HN patients have been enrolled to a prospective trial, 10 received SMG transfer and 6 patients served as controls. All patients were treated with VMAT. Mean doses to SMG and parotid glands were extracted from treatment plans and weekly CBCT for SMG transfer patients to assess dosimetric stability of the dose to the transferred gland. Stimulated and unstimulated salivary flow, quality of life data (xerostomia XeQoLS questionnaire), eating assessment (EAT-10), and performance status scale for HN cancer patients (PSS-HN), were collected at baseline before RT started, and at 3, 6 and 12 months after completion of RT. Results Parotid gland sparing was similar, mean doses to spared and non-spared glands were 18.2±4.5 and 29.2±8.1Gy among transfer patient; 17.9±6.5 and 28.2±8.33Gy among controls. Doses to non-spared SMG were 68.8±2.6 and 68.4±5.0Gy. Significant reduction of mean dose to the transferred SMG was achieved in planning, 17.9±4.8Gy vs 47.6±18.3, p<0.01. No difference was seen for any salivary flow or QoL tests at baseline. As a trend, SMG transfer patients showed improved salivary flow function and more pronounced recovery, albeit with significant patient-to-patient variation. Unstimulated saliva flow (g/min), which is primarily due to SMG, was 0.20±0.14, 0.30±0.21 and 0.42±0.38 at 3, 6 and 12 months among SMG transfer patients. Among controls the flow was 0.17±0.07, 0.20±0.04 and 0.21±0.16 g/min. A similar trend was observed when flow was expressed relative to baseline. Xerostomia, eating assessment and performance status scale scores also indicated improved QoL among patients receiving SMG transfer. XeQoLS score was 12.7±8.4 and 8.7±6.9 at 3 and 6 months among SMG transfer patients compared to 18.5±15.5 and 11.0±9.2 among controls with a similar trend for EAT-10 scores. PSS-HN scores among SMG transfer patients at 6 and 12 months were 82.8±18.2 and 93.1±12.8 (normalcy of diet), 88.9±18.2 and 96.9±8.8 (public eating). Among controls these scores were 62.5±22.2 and 65.0±26.5 (normalcy of diet), 83.3±28.9 and 90.0±22.3 (public eating). While the trends were consistent, differences were not statistically significant at the time of analysis. Patients are being enrolled to the control group with a goal of 10 patients. Of note, two SMG transfer patients who showed slow salivary flow recovery also showed significant increase in mean dose to the spared SMG based on CBCT analysis, from <20Gy to >30Gy. The increased dose was due to head tilt and lower jaw position. Conclusion Patients receiving SMG transfer trended towards improved salivary flow and QoL scores compared to controls, although the differences were not significant. Actual dose to the transferred SMG in two of ten patients was substantially larger than in RT plan, attributable to patient position. Purpose or Objective Radiation-induced Xerostomia could impair speech, tasting, and swallowing and thus alteration of the quality of life of long survivors. The study aimed to identify dosimetric predictors for the persistence of xerostomia in patients with nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT). Materials and Methods This prospective study included 45 patients diagnosed with non-metastatic NPC between June 2017 and February 2020. All patients received neoadjuvant chemotherapy followed by concurrent chemoradiation according to an IMRT technique. Clinical assessment of xerostomia and measurement of salivary flow was performed at the end of the RT sessions, 1, 3, and 6 months later. Xerostomia was assessed using the Radiation Therapy Oncology Group criteria. Predictors for persistent xerostomia were analyzed using the Khi-Deux test. Receiver operating characteristic curve analysis was used to identify the most appropriate cut-off values for predicting factors. Results At the end of RT, all patients experienced xerostomia (29 (64.5%) were of grade ≥ 2). At the end of the follow-up (6 months), persistent grade 2 xerostomia was noted in 18/40 patients (45%). No patient maintained a G3 xerostomia. Predictors for persistent xerostomia were mean dose (Dmean) and D50 for both parotid glands after excluding PTV volume with a cut-off of 31 Gy and 25 Gy respectively. PO-1197 Dosimetric predictors of persistent xerostomia after IMRT for nasopharyngeal carcinoma N. Fourati 1 , S. Zouari 1 , M. Frikha 1 , Z. Fessi 1 , W. Siala 1 , W. Mnejja 1 , J. Daoud 1 1 Habib Bourguiba Hospital Faculty of Medicine University of Sfax, Radiotherapy Department, Sfax, Tunisia