ESTRO 2022 - Abstract Book

S751

Abstract book

ESTRO 2022

experimental treatment. The DAHANCA 27 trial is a comparative non-inferiority phase II study comparing two timely separated national patient cohorts. Patients treated with radical TLM in the DAHANCA 27-protocol from September 2012 to April 2016 were included in the TLM cohort, and patients treated with accelerated RT from January 2003 to august 2012 were included in the RT cohort. All patients were followed for five years or until death. All Danish patients diagnosed with a head and neck cancer are prospectively registered in the DAHANCA (Danish Head and Neck Cancer) database. Hence, all patients diagnosed with a T1aN0M0 glottic SCC are registered, allowing for the analyses of potential selection biases into the DAHANCA 27 study cohorts. The primary endpoint was 5-year laryngectomy free survival. Results A total of 94 patients were included in the TLM cohort and 553 patients in the RT cohort. With an observation time of 60 month, the proportion of recurrence was 9,6 % (9 patients /94) in the TLM cohort and 7,2 % (40 patients/ 553) in the RT cohort. The proportion of patients with ultimate failure was 2,1 % (2/94 patients) in the TLM cohort and and 3,1 % (17/553 patients) in the RT cohort. One of the two patients in the TLM cohort with non-cured recurrence initially rejected salvage treatment and became incurable. Laryngectomy was performed in 2 patients in the TLM cohort and 16 patients in the RT cohort. In total 81 and 100 patients in the TLM and RT cohorts were eligible for voice handicap index evaluation 3 years after the primary treatment, hereof 51 and 39 completed the questionnaire in the two groups respectively. No differences in the overall VHI score or sub-scale sores were observed. After further data analysis, the 5-year laryngectomy free survival will be reported as will the secondary endpoints local control, locoregional control, disease specific survival, and GRBAS (grade, roughness, breathiness, asthenia, strain) voice scale. Conclusion Many smaller studies have shown similar tumor control rates after TLM and RT respectively, but no randomized trial have been published reporting tumor control, laryngectomy rate or survival as the primary endpoint. This study will contribute to the international evidence regarding best practice in the treatment of T1aN0M0 glottic cancer due to the large national cohorts. C. Gani 1 , B. Polat 2 , O. Ott 3 , E. Germer 4 , A. Königsrainer 5 , A. Kirschniak 6 , S. Clasen 7 , U. Grosse 8 , M. Diefenhardt 9 , M. Bitzer 10 , J. Reibetanz 11 , P. Martus 12 , M. Flentje 2 , R. Fietkau 3 , E. Fokas 9 , D. Zips 1 , C.M. Rödel 9 1 University Hospital Tübingen, Department of Radiation Oncology, Tübingen, Germany; 2 University Hospital Würzburg, Department of Radiation Oncology, Würzburg, Germany; 3 University Hospital Erlangen, Department of Radiation Oncology, Erlangen, Germany; 4 University Hospital Würzburg, Comprehensive Cancer Center, Würzburg, Germany; 5 University Hospital Tübingen, Department of general, visceral and transplant surgery, Tübingen, Germany; 6 Kliniken Maria Hilf , Surgical Department, Mönchengladbach, Germany; 7 Klinikum am Steinenberg, Institute for Diagnostic and Interventional Radiology, Reutlingen, Germany; 8 Spital Thurgau , Radiology, Frauenfeld, Switzerland; 9 University Hospital Frankfurt, Department of Radiation Oncology, Frankfurt, Germany; 10 University Hospital Tübingen, Department of Gastroenterology, Tübingen, Germany; 11 University Hospital Würzburg, Department of general, visceral and transplant surgery, Würzburg, Germany; 12 University Hospital Tübingen, Institute for clinical epidemiology and applied biometry, Tübingen, Germany Purpose or Objective Total neoadjuvant therapy (TNT) has recently shown to considerably increase pathological complete response (pCR) rates after surgery. However, data on the impact of TNT on clinical complete response (cCR) rates to facilitate subsequent organ preservation remain limited. Materials and Methods This multicenter phase II trial assessed the clinical response after long-course radiochemotherapy (50.4 Gy and concomitant 5-FU/Oxaliplatin) followed by three cycles of consolidation chemotherapy with mFOLFOX6. Patients with stage II or III rectal cancer were enrolled. The primary endpoint was cCR rate on day 106 or day 196 (in case of a near CR on d106) after the start of treatment. Secondary endpoints include compliance, toxicity, pathological complete response, and long-term oncologic outcomes. Results A total of 93 patients were enrolled, 91 patients were evaluable. Of those 91 patients, 99% received full-dose radiotherapy, 70.3% received full-dose concomitant chemotherapy and 83% received all three cycles of consolidative chemotherapy. Grade III- IV toxicity during TNT was observed in 45% of patients. On day 106, 15% of patients had achieved a cCR and 38% were found to have a near cCR. After re-assessment on day 196, 21 of the 30 (70%) patients with a near cCR on day 106 had further regressed to a cCR. Another two patients underwent local excision after restaging on day 196 and were found to have a pCR. In total 36 of 91 (40%) patients qualified for omission of major surgery after TNT. Conclusion TNT with long-course radiotherapy and consolidative chemotherapy results in high cCR rate in patients with locally advanced rectal cancer. Results for sustained cCR and local regrowth rates require longer follow-up. ClinicalTrials.gov Identifier: NCT03561142 OC-0833 Total neoadjuvant therapy for Organ Preservation in Rectal Cancer: The CAO/ARO/AIO-16 phase II trial