ESTRO 2022 - Abstract Book

S947

Abstract book

ESTRO 2022

Hospital Frankfurt, Department of Otorhinolaryngology, Frankfurt, Germany; 8 University Hospital Frankfurt, Department of Oral, Maxillofacial and Facial Plastic Surgery, Frankfurt, Germany; 9 University Hospital Frankfurt, Department of Radiotherapy and Oncology , Frankfurt, Germany; 10 University Hospital Zurich, Department of Radiation Oncology, Zurich, Switzerland Purpose or Objective To study neoadjuvant chemoradiotherapy (nCRT) and potential predictive factors for response to therapy in locally advanced oral cavity cancer (LA-OCC). Materials and Methods The INVERT trial is an ongoing single-center, prospective trial. Operable patients with stage III-IVA squamous cell carcinomas of the oral cavity or oropharynx were eligible and received nCRT consisting of 60Gy with concomitant cisplatin and 5- fluorouracil administration. Surgery was conducted 6-8 weeks following nCRT. Explorative, multiplex immunohistochemistry (IHC) was performed on pre-treatment tumor tissue specimens and diffusion-weighted magnetic resonance imaging (DW- MRI) was performed prior, during, and after nCRT in order to identify potential predictive biomarkers. Primary endpoint was pathological complete response (pCR) rate. Results Seventeen patients with stage IVA OCC were enrolled and included into this interim analysis. All patients completed nCRT. One patient died from pneumonia ten weeks after nCRT completion. Complete tumor resection (R0) was achieved in 16/17 patients who underwent surgery. pCR rate was 41% in the intention-to-treat population (n=7). Greater changes in the apparent diffusion coefficient signal intensities between MRI at day 15 of nCRT and before surgery were associated with better response (p=0.022). Higher abundances of PD1+ cytotoxic T-cells (p=0.012), PD1+ macrophages (p=0.046), and cancer-associated fibroblasts (CAFs, p=0.036) were associated with incomplete response to nCRT. Conclusion nCRT for LA-OCC followed by radical surgery is feasible and shows high response rates. Larger patient cohorts from randomized, controlled trials are needed to further investigate nCRT and potential predictive biomarkers such as changes in DW-MRI signal intensities, tumor infiltrating immune cells, and CAFs. D. Alterio 1 , S. Vigorito 2 , F. Emiro 2 , M.G. Vincini 1 , A. Ferrari 1 , S. Marani 1 , M. Pepa 1 , M. Zaffaroni 1 , C. Fodor 1 , S. Volpe 3 , G. Marvaso 3 , L. Bergamaschi 3 , C. Pedone 3 , J. Franzetti 3 , S. Zorzi 4 , M. Tagliabue 4 , M. Ansarin 4 , B.A. Jereczek-Fossa 3 1 IEO European Institute of Oncology IRCCS, Division of Radiation Oncology, Milan, Italy; 2 IEO European Institute of Oncology IRCCS, Unit of Medical Physics, Milan, Italy; 3 IEO European Institute of Oncology IRCCS, University of Milan, Division of Radiation Oncology, Department of Oncology and Hemato-Oncology, Milan, Italy; 4 IEO European Institute of Oncology IRCCS, Division of Otolaryngology and Head and Neck Surgery, Milan, Italy Purpose or Objective Patients (pts) with locally advanced supraglottic cancers (LASGC) treated with conservative surgery (CS) followed by postoperative 3D conformal radiotherapy (3DCRT) could be affected by high rate (up to 30%) of severe long-term treatment- related side effects. Data on the impact of Intensity Modulated Radiotherapy (IMRT) in improving the toxicity profile are lacking. Aim of the present analysis was to report long-term toxicity of pts with LASGC treated with CS followed by postoperative IMRT. Dosimetric comparison between IMRT and 3DCRT was also performed. Materials and Methods Data of pts treated from 2014 to 2020 with CS and postoperative IMRT for locally advanced (stage III and IV according to AJCC 7 th Ed) cancers of the supraglottis have been prospectively collected. Exclusion criteria were: 1) early-stage (stage I and II) disease; 2) recurrent tumours; 3) previous treatments on head and neck region; 5) follow-up shorter than 6 months. Simultaneous Integrated Boost (SIB)-IMRT was performed using Volumetric Modulated Arc Therapy (VMAT) technique; to make the comparison, a 3DCRT plan was calculated for each of pts using a shrinking field technique with the same IMRT dose levels. Swallowing-related structures (SWARs) and Swallowing Functional Units (SFUs) were retrospectively contoured on each patient. Post-hoc Wilcoxon-signed-rank tests (p-value < 0.05) were used to perform a comparison between maximum and mean doses (dMax and dMean, respectively) of IMRT and 3DCRT treatment plans to assess possible differences between absorbed doses to remnant larynx (RL), arytenoids, SWARS, and SFUs. Results Twenty pts have been analysed. Advanced tumor (pT3/4) and advanced nodal (pN2/3) stages were found in 13 and 11 pts, respectively. Median follow-up was 33 months (range 8-92 months). At last follow up, 15 pts were alive without disease, 5 pts died (2 for progression and 3 for other causes). During the follow-up course, 5 (20%) pts required temporary tracheostomy while 2 (10%) pts required both temporary tracheostomy and enteral nutrition. At last follow up one patient (5%) had still in place both tracheostomy and percutaneous endoscopic gastrostomy (PEG). No patient had esophageal stricture and/or chondronecrosis. Results of dosimetric comparison have been reported in Table1. Both IMRT dMax and dMean resulted significant lower compared to 3DCRT technique according to Wilcoxon-signed rank test for 7 structures (LR, arytenoids, thyroid muscles, and submandibular glands); relative boxplots are displayed in Fig1. PO-1114 Intensity Modulated Radiotherapy (IMRT) after conservative surgery for supraglottic tumours