ESTRO 2021 Abstract Book

S249

ESTRO 2021

Conclusion Neither arm demonstrated evidence of superior safety, efficacy or symptom burden. SF SABR is likely to be cost-effective at common thresholds of cost-effectiveness. Trial Registration: Clinicaltrials.gov ID:NCT01965223 OC-0336 Dose escalated chemoradiotherapy in esophageal cancer : randomized phase 2/3 CONCORDE trial G. Crehange 1 , C. M'vondo 2 , A. Bertaut 3 , R. Pereira 4 , E. Rio 5 , D. Peiffert 6 , K. Gnep 7 , K. Benezery 8 , P. Ronchin 9 , G. Noel 10 , L. Mineur 11 , A. Drouillard 12 , J. Blanc 3 , M. Rouffiac 13 , J. Boustani 14 1 institut Curie, Radiation Oncology, Paris, France; 2 centre François Baclesse, Radiation Oncology, Caen, France; 3 centre Georges François Leclerc, Biostatistics, Dijon, France; 4 centre Guillaume Le Conquerant, Radiation Oncology, Le Havre, France; 5 institut De Cancérologie De L'ouest, Radiation Oncology, Nantes, France; 6 institut De Cancérologie De Lorraine, Radiation Oncology, Nancy, France; 7 Centre Eugène Marquis, Radiation Oncology, Rennes, France; 8 Centre Antoine Lacassagne, Radiation Oncology, Nice, France; 9 Azuréen Cancer Center, Radiation Oncology, Mougins, France; 10 ICANS, Radiation Oncology, Strasbourg, France; 11 Institut Sainte Catherine, Radiation Oncology, Avignon, France; 12 CHU F Mitterrand, Gastroenterology, Dijon, France; 13 Centre Georges François Leclerc, Radiation Oncology, Dijon, France; 14 CHRU Jean Minjoz, Radiation Oncology, Besançon, France Purpose or Objective Benefits and harms of radiation dose escalated chemoradiotherapy in advanced esophageal cancer unsuitable for surgery remains unclear in the last 2 decades. We conducted a randomised phase 2/3 trial to conclusively address this issue. Materials and Methods 217 patients were enrolled from 28 centres in France between 07/06/2011 and 11/10/2019. Eligible participants had confirmed stage I-III biopsy proven esophageal carcinoma, ECOG 0-2 and sufficient caloric intake. Patients were randomly assigned (1:1) to receive 50Gy in 25 fractions over 5 weeks (standard arm) or 66Gy in 33 fractions over 6.5 weeks (experimental arm). Elective nodal irradiation (40Gy) was delivered in both groups. Concomitant chemotherapy was FOLFOX-4 for 3 courses followed by 3 adjuvant courses. In this analysis, we report on secondary outcomes of the trial : non haematological late toxicity, survival and causes of deaths. Results 109 participants were randomly allocated to the 50Gy arm and 108 to the 66Gy group (intention-to-treat population). 191 patients (88.4%) had squamous cell cancer and 25 (11.6%) had adenocarcinoma. Most of the patients had stage III tumors (74% vs 26% for stage I-II). IMRT was delivered in 169 patients (80.1%) and 3D conformal in 42 patients (19.9%). Among 153 evaluable patients for late toxicity, there was no significant difference between the 2 groups (p= 0.22). The rates of grade 2 were 41.0% and 37.3% in the 50Gy and the 66Gy arms, respectively. The rates of grade 3 were 29.5% and 24.0%, respectively. No grade 4 was observed in the 50Gy group and 3 patients had a grade 4 in the 66Gy group. Grade ≥ 3 esophageal stenosis occurred in 5 patients in the 50Gy arm and 7 patients in the 66Gy arm. Fistula occurred only in 2 patients, both in the 66Gy group (p=0.24). 5 toxic deaths (4.6%) occurred in the 50Gy group and 7 (6.7%) in the 66Gy group.