ESTRO 2023 - Abstract Book

S946

Digital Posters

ESTRO 2023

1 All India Institute of Medical Sciences- Jhajjar, Radiation Oncology, New Delhi, India; 2 All India Institute of Medical Sciences- Jhajjar, Medical Physics, New Delhi, India Purpose or Objective Locoregionally advanced head and neck carcinomas (HNC) are ideal candidates for dose escalation with radical chemoradiotherapy (CRT). We escalated radiation dose to 2.33 Gy per fraction (70 Gy in 30 fractions) in N3 disease while trying to maximally spare adjoining swallowing organs at risk. We herein present the dosimetric results and treatment outcomes in this subset of patients. Materials and Methods A total of 23 oropharyngeal and 3 laryngeal cancer patients presented to the department with advanced nodal disease (N3). Given the high volume of disease burden coupled with increased chances of infield failure, all patients opted for dose escalation SIB IMRT. Swallowing and aspiration related structures delineated included constrictors muscles, base of tongue, cricopharyngeus muscles, esophageal inlet, cervical esophagus, supraglottic larynx and larynx. Xerostomia related structures contoured included bilateral parotid & submandibular glands. Target delineation was done as per recent consensus guidelines by Gregoire et al 2018. Swallowing & contralateral submandibular gland sparing double arc VMAT based therapy was delivered to all patients. A dose of 70 Gy in 30 fractions was delivered to N3 disease whereas the primary tumor received 66 Gy and microscopic disease received 54 Gy in 30 fractions. Results The median nodal volume was 39.7 cc (range 3.3 - 81.8 cc) and median primary tumor volume was 23.6 cc (range 6.8 - 62.8 cc). Median D mean dose to contralateral submandibular gland was 41.3 Gy (IQR: 36.5 - 53 Gy). D mean doses to organs at risk were as follows- median superior constrictor dose was 49.8 Gy (IQR: 43 - 56.3 Gy), median middle constrictor dose was 55 Gy (IQR: 48.8 - 62.3 Gy), and median inferior constrictor dose was 42 Gy (IQR: 30 - 52.5 Gy). Median D mean dose to base of tongue was 58.7 Gy (IQR: 40.5 - 64.3 Gy). Median SGL D mean dose was 53.4 Gy (IQR: 41.6 - 64.5 Gy), median larynx D mean dose was 33.1 Gy (IQR: 28.9 - 47.5 Gy), and median cricopharyngeus D mean dose was 37.2 Gy (IQR: 28.4 - 44.4 Gy). Remaining D mean doses were- median esophageal inlet dose was 32.3 Gy (IQR: 28.4 - 39.7 Gy), median cervical esophagus dose was 27 Gy (IQR: 19.7 - 30.4 Gy), median L parotid dose was 26 Gy (IQR: 21.9 - 38.5 Gy), and median R parotid dose was 26.7 Gy (IQR: 24.1 - 34.9 Gy). Median follow-up was 176 days (range= 1 - 689). One year OS was 71.8% (95% CI= 53.9 - 95.6%). One year LC and RC were 87.5% (95% CI= 67.3 - 100%) and 66.1% (95% CI= 45.2 - 96.7%) respectively. All loco-regional failures occurred inside the high dose volume region; there were no marginal recurrences. Acute grade 3 or higher dysphagia and mucositis developed in 10 and 7 patients respectively. Late Grade 3 dysphagia and mucositis developed in 2 (15.4%; n= 13) and 0 patients respectively. Conclusion The study demonstrates that dose escalation to high volume nodal disease is safe and feasible. All loco-regional failures occurred inside the high dose region and there were no marginal recurrences in the present study. 1 Sahyadri superspecialty hospital , Radiation Oncology, pune, India; 2 sahyadri superspecialty hospital, Radiation Oncology, pune, India; 3 sahaydri superspecialty hospital, Radiation oncology, pune, India; 4 sahyadri superspecialty hospital, Medical physics, pune, India Purpose or Objective Radiation plays an important role in the definitive treatment of various head and neck cancers. The innovations of new techniques like IMRT, IGRT , VMAT has significantly reduced toxicity profile of patients treated with radiotherapy.Most common complications which are seen during radiation include dermatitis , mucositis dysphagia, xerostomia .Though most patients recover quality of life by 12 months, deterioration in physical functioning, fatigue, xerostomia, and sticky saliva persist beyond 12 months in head and neck cancer survivors . Temporally Feathered Radiation Therapy (TFRT) has been proposed as a technique to reduce toxicity in patients undergoing radiation therapy to the head and neck. In IMRT we optimize the physical distribution of radiation dose, in TFRT optimisation is done to the time through which radiation therapy is delivered and take advantage of the non-linear recovery of normal tissues Materials and Methods Patients with HNSCC of oropharynx treated with definitive radiation therapy were eligible (70 Gy in 35 fractions) were eligible. The primary endpoint was feasibility of TFRT planning as defined by radiation start within 5-7 days days of CT simulation. Secondary endpoints included estimates of acute toxicities Results • We analysed 10 patients, with a follow up period of 10 months . TFRT plans were generated for all ten patients within one week of CT simulation, therefore meeting the primary endpoint. For patients who received TFRT, the median time from CT simulation to radiation start was 3 business days (range 2–5). In all patients receiving TFRT, each subplan and every daily fraction was delivered in the correct sequence without error. The OARs feathered included: oral cavity, each submandibular gland, each parotid gland , and posterior pharyngeal wall (OAR pharynx), Larynx. Prescription dose PTV coverage (>95%) was ensured in each TFRT subplan and the composite TFRT plan. None of the patients had more than grade 3 and 4 toxicities.We compared these toxicities in TFRT IMRT plans to previously executed standard IMRT plans ( which was used as control ) and found that in previously treated standard IMRT plans majority had grade 3 and 4 toxicities. PO-1183 Feasibility of Temporally Feathered Radiation Therapy (TFRT) planning in head and neck cancers S. hunugundmath 1 , M. deputy 2 , S. upadhye 3 , A. nirhali 4 , V. naik 4

Made with FlippingBook flipbook maker