ESTRO 2023 - Abstract Book

S948

Digital Posters

ESTRO 2023

Conclusion In our experience, multiple hypofractionated Re-RT schedules were shown to be a well tolerated treatment option for HNC recurrence with potential for prolonged local control in appropriately selected patients.

PO-1185 Long term effectiveness of intraoperative radiotherapy boost in adjuvant treatment for oral cancers

G. Wozniak 1 , T. Rutkowski 1 , W. Majewski 1 , T. Latusek 1 , S. Blamek 1 , Z. Kaniszewska-Dorsz 1 , A. Czarnecka 2 , C. Szymczyk 2 , J. Wierzgon 2 , A. Bekman 3 , B. Wozniak 3 , A. Orlef 3 , M. Kijonka 3 , A. Napieralska 1 , J. Wydmanski 1 1 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice branch, Radiotherapy Department, Gliwice, Poland; 2 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice branch, Oncologic and Reconstructive Surgery Clinic, Gliwice, Poland; 3 Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice branch, Medical Physics Department, Gliwice, Poland Purpose or Objective Evaluation of the effectiveness of intraoperative radiotherapy (IORT) boost for patients with oral cavity cancer. Materials and Methods Retrospective analysis of 26 patients (pts) with pathologically diagnosed oral cavity squamous cell carcinoma (SCC) treated between 2003 and 2019 was performed. Patients were treated with X-ray 50kV radiotherapy boost delivered during surgery. All patient underwent adjuvant external beam radiotherapy (EBRT) to the tumor bed and lymph nodes to the median total dose of 50Gy. Male to female ratio was 1.3. Median age was 66 years. In 14 patients tumor was located in a mobile tongue and in 9 patients in a floor of mouth. All patients underwent tumorectomy, in 20 cases lymphadenectomy (mainly suprahyoid) was performed additionally. Pathologic stage pT1 was noted in 14 pts , pT2 in 8, and in 1 case pT3 was established. After surgical procedure and intraoperative evaluation of margins, all patients were irradiated using 50kV beams delivered by miniature x-ray generator (IntraBeam™) given as single dose ranged between 5 to 7.5 Gy (depending on a margin status), to high risk area and specified 5mm from the applicator surface. A diameter of the applicator ranged between 2,5 and 4 cm, and was selected after tumor excision to encompass entire tumor bed. Mean treatment time was 12.5 min. Local control (LC), loco-regional control (LRC), and survival OS and DFS were estimated with Kaplan Maier method and compared with log-rank test. Results Median follow up was 164 months. Early tolerance was good: 5 patients developed superficial mucosal erosion (G3) due to small distance between mucosal edges of tumor bed and applicator surface, which healed completely before EBRT. No significant ≥ G3 late effects was observed. One patient had local recurrence alone, in two patients nodal metastases and in one patient both local and regional relapse were observed. Distant metastases developed in two patients. Two patients were deceased due to lung cancer, another one patient also developed lung cancer, underwent thoracotomy and is still under observation with no evidence of disease from both cancers. Ten year LC, LRC, DFS, OS was 93%, 84% and 40% and 54%, 15-year LC ,LRC, DFS was 83%, 73% and 40% and 47%. There were no significant differences in LC and DFS depending on T stage (p=0.34; 0.57), grading (p=0.22; 0.18), tumor location (p=0.64; 0.44) and boost dose (p=0.5; 0.93), probably due to small number of pts.

Conclusion Low energy IORT is safe and effective boost modality in oral cavity cancers

PO-1186 Predictors for laryngo-esophageal function preservation after radiotherapy for hypopharyngeal cancer

A. Nakajima 1 , S. Hiraoka 1 , R. Nakashima 1 , M. Yoshimura 1 , T. Mizowaki 1

1 Kyoto University Graduate School of Medicine, Department of Radiation Oncology and Image-Applied Therapy, Kyoto, Japan