ESTRO 2022 - Abstract Book

S932

Abstract book

ESTRO 2022

The objective of this study was to evaluate the efficacy of low-level Helium-Neon laser for the treatment of radiation induced oral mucositis and reducing pain associated with it in oral cavity cancer patients. Materials and Methods 60 patients with oral cavity cancer undergoing post-operative radiotherapy without concurrent chemotherapy were enrolled in the present study and assigned to the laser (Group 1)/ control (Group 2). All patients received proper nutrition counseling, mouth wash containing betadine and bendydamine and painkillers were given according to the WHO pain ladder. After developing grade 2 mucositis, Group 1 received low level Helium-Neon laser therapy (wavelength- 630nm, frequency- 1500 Hz, intensiy- 100% and energy- 396.364 Joule) daily 1 hour before receiving radiation. The laser was directed in the oral cavity and the whole oral mucosa was treated. Patients were made to wear googles to protect the eyes from the laser beam. The patients were monitored for oral mucositis (RTOG grading), pain severity (Numerical Pain Rating Scale) and weight reduction on every 3rd day during radiotherapy. Statistical analysis of parameters between two groups was done using SPSS version 22 software and R environment ver.3.2.2. Patients in Group 1 experienced lower grade of mucositis at the end of each week as compared to Group 2. At the end of week 4, more patients in Group 2 progressed to grade 3 mucositis as compared to Group 1 (80% vs 3.3%, p<0.001). At the end of week 5, almost all patients in Group 2 developed grade 3 mucositis (96.7% vs 56.7%, p<0.001). On completion of radiotherapy, 90% patients in Group 2 had grade 3 and 10% had grade 4 mucositis as compared to only 56.7% and 3.3% respectively in Group 1 (p<0.001). • The mean dose of radiotherapy which led to development of grade 3 mucositis was significantly more in Group 1 (43.92 Gy vs 35.47 Gy, p<0.001). • Pain associated with mucositis was significantly reduced during and on completion of radiotherapy in the patients receiving laser therapy. At the end of radiotherapy, 73.3% in Group 2 had pain score > 5 as compared to only 26.7% in Group 1 (p<0.001) which resulted into significantly lower number of patients requiring higher painkillers in Group 1. • The mean number of days of WHO step 2 painkiller requirement was 3.2 vs 7.8 days in Group 1 and 2 respectively (p=0.004). • Patients in Group 1 had lesser treatment interruption due to severe mucositis as compared to Group 2 (p=0.029). Conclusion Laser therapy for radiation induced oral mucositis may prove useful in the treatment of oral cavity cancers by treating mucositis and hence reducing the treatment interruptions providing better tumour control, reducing the pain associated with it and improving the quality of life of patients. Results • Laser therapy significantly delayed the progression of mucositis from grade 2 to grade 3 (p<0.001). • 1 Region Västra Götaland, Sahlgrenska University Hospital, Dept of Medical Physics and Biomedical Engineering, Gothenburg, Sweden; 2 Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Department of Medical Radiation Sciences, Gothenburg, Sweden; 3 Head and Neck surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Department of Otorhinolaryngology, Gothenburg, Sweden; 4 Region Västra Götaland, Sahlgrenska University Hospital, Department of Otorhinolaryngology, Gothenburg, Sweden; 5 the Western Sweden Healthcare region, Sahlgrenska University Hospital, Regional Cancer Center West, Gothenburg, Sweden Purpose or Objective Doses to mastication structures critical for radiation-induced trismus in head and neck cancer (HNC) depend on radiation therapy (RT) technique. Doses by older, less conformal, RT techniques often exceeded currently proposed tolerance doses, but it is unknown how newer techniques fare in this context. The purpose of this work was to investigate how doses to the temporomandibular (TM) joint, masseter muscles, and pterygoid muscles in VMAT for HNC compared to earlier RT techniques. Materials and Methods We investigated two HNC patient cohorts treated with external beam RT at the Sahlgrenska University Hospital, Sweden, in 2007-2012 (3D-CRT and/or IMRT; n=195 [study 1]) or 2017-2020 (VMAT; n=117 [study 2]). All patients had undergone RT without mastication-structure-sparing intent. All included patients had normal mouth-opening ability before RT and were followed up with respect to trismus status at 3, 6 and 12 months post RT. Trismus was defined as maximal interincisal opening [MIO] ≤ 35 mm at any post-RT follow up. The TM joint, masseter and medial/lateral pterygoid muscles were consistently delineated on the planning CT:s. Mean dose comparisons for structures were made using Student’s unpaired t- test. P-values ≤ 0.05 indicated statistical significance. Results Within 12 months post RT, 109/195 (56%) of patients in study 1 had experienced trismus compared to 15/117 (13%) in study 2. Averaged mean doses (±1 SD) for the masseter muscles were 17.6±4.5 Gy in study 1 and 10.0±4.6 Gy in study 2 (p<0.001). Corresponding numbers were 8.5±7.6 Gy and 2.3±2.5 Gy for the TM joints (p<0.001), 25.9±5.1 Gy and 19.1±8.4 Gy for the medial pterygoid muscles (p<0.001), and 13.0±9.0 Gy and 4.8±4.8 Gy for the lateral pterygoid muscles (p<0.001). Masseter muscle doses were above the proposed tolerance in 73% of patients in study 1 compared to 12% in study 2 ( Figure 1 ). The corresponding numbers were 44% and 6% for the TM joints, 88% and 58% for the medial pterygoid muscles and 22% and 1% for the lateral pterygoid muscles. PO-1098 Head and neck cancer mastication structure doses by older and newer external beam RT techniques N. Pettersson 1,2 , N. Pauli 3,4 , E. Andersson 3 , L. Tuomi 4,3 , C. Finizia 4,3 , C. Olsson 2,5