ESTRO 2022 - Abstract Book

S82

Abstract book

ESTRO 2022

the optimal preoperative strategy in resectable gastric cancer by comparing 3 arms. A preplanned interim analysis (IA) was performed and reviewed by the Independent Data Safety Monitoring Committee to determine any imbalances between the 3 arms that could necessitate the discontinuation of any of the treatment arms. Materials and Methods CRITICS-II is a randomised phase II trial evaluating 3 experimental preoperative treatment arms independently according to the “pick the winner” principle. Patients are randomised to: 4 cycles of docetaxel/oxaliplatin/capecitabine (DOC); 2 cycles of DOC followed by CRT (45 Gy with weekly carboplatin/docetaxel; DOC-CRT); or CRT only. Primary endpoint is event-free survival at 1 year; secondary endpoints are time to event, time to recurrence, R0 resection rate, pCR rate, complications, toxicity and overall survival. Here, we report the results of the IA with a focus on baseline characteristics, patient compliance, surgical and pathology details, complications and toxicity. Results At a median follow-up of 14 months, 119 randomised patients were eligible for this IA. No significant imbalances were found in baseline characteristics. Completion of preoperative treatment for the total group was 89%. Main reasons for not completing preoperative treatment were toxicity (n=7), death (n=2), disease progression (n=1) and patient’s refusal (n=1). Surgery was performed in 92% of patients. Reasons for not proceeding to surgery were disease progression (n=4), toxicity (n=3) and patient’s refusal (n=1). Surgery was with curative intent in 99% of patients, and involved a total gastrectomy in 51% and a D2 lymph node dissection in 93%. In-hospital mortality was 6%. Surgical complications occurred in 18% and consisted of anastomotic leakage (n=7), bleeding (n=2), fistula (n=1), ileus (n=1), necrosis (n=1) and other (n=5). R0 resection was obtained in 95% and the median number of lymph nodes was 22. The percentage of patients who completed treatment according to protocol was 80% for the total group. Main reasons for not completing were disease progression (6%), toxicity (5%), death (5%) and patient’s refusal (1%). Maximum grade 3-5 any toxicity was 61%; grade 5 toxicity was 8%. Cause of death was of infectious (n=5) or pulmonary (n=4) origin. Conclusion Interim results from the CRITICS-II trial showed a high patient compliance rate. Treatment-related toxicity and surgical morbidity were significant, but in line with previous studies. No major imbalances were detected between the 3 preoperative treatment arms; accrual continues as planned up to a total of 207 patients. H. LOPEZ 1 , G. Créhange 2 , J. Blanc 3 , C. M'vondo 4 , R. Pereira 5 , E. Rio 6 , D. Peiffert 7 , K. Gnep 8 , K. Benezery 9 , P. Ronchin 10 , G. Noel 11 , L. Mineur 12 , A. Drouillard 13 , M. Rouffiac 14 , J. Boustani 15 , A. Bertaut 16 , F. Huguet 1 1 Tenon Hospital, Radiation Oncology, Paris, France; 2 Institut Curie, Radiation Oncology, Paris, France; 3 Centre Georges François Leclerc, Biostatistic, Dijon, France; 4 Centre François Baclesse, Radiation Oncology, Caen, France; 5 Centre Guillaume Le Conquérant, Radiation Oncology, Le Havre, France; 6 Institut de Cancérologie de l’Ouest, Radiation Oncology, Saint-Herblain, France; 7 Institut de Cancérologie de Lorraine, Radiation Oncology, Nancy, France; 8 Centre Eugène Marquis, Radiation Oncology, Rennes, France; 9 Centre Hospitalier Princesse Grace, Radiation Oncology, Monaco, Monaco; 10 Clinique Plein Ciel, Radiation Oncology, Mougins, France; 11 Institut de cancérologie Strasbourg Europe, Radiation Oncology, Strasbourg, France; 12 Institut Sainte Catherine, Radiation Oncology, Avignon, France; 13 Centre Hospitalo Universitaire, Radiation Oncology, Dijon, France; 14 Centre Georges François Leclerc, Radiation Oncology, Dijon, France; 15 CHRU Jean Minjoz, Radiation Oncology, Besançon, France; 16 Centre Georges François Leclerc , Biostatistic, Dijon, France Purpose or Objective The CONCORDE phase 2-3 trial assessed the benefit of radiation therapy dose escalation in locally advanced esophageal cancer patients that cannot undergo surgery. This planned analysis investigated the adherence to the radiation therapy protocol and its impact on the clinical outcomes as part of the quality assurance of the trial. Materials and Methods The trial’s radiation therapy quality assurance (RTQA) protocol included written guidelines on how to deliver radiation therapy. We analyzed each patient’s delineation, dose-volume histogram, and treatment administration. Adherence to protocol was classified as: per protocol (PP), acceptable minor deviation (MiD), or unacceptable major deviation (MaD). The impact of protocol deviations on overall survival (OS), progression-free survival (PFS), acute toxicities, and late toxicities was studied. Results Among the 217 patients included, 181 case reviews (83.4%) were assessed: 28 patients were classified PP (15.5%), 70 MiD (38.7%), and 83 MaD (45.8%). Patients with tumors longer than 5 cm had significantly more MaD than the others (p= 0.0032). There was significantly more MaD in the escalated dose arm than in the standard arm (53.9% vs. 38%, p=0.03). In the dose escalated arm, there was significantly more MaD regarding PTV coverage (15.7% vs 6.5% p=0.04) and more patients not receiving the prescribed RT dose than in the control arm (11.2% vs 6.5%, p=0.08). Among patients treated with 3DCRT, none were classified as PP and the rate of patients with MaD was higher than with IMRT (60% vs 42.5%, p=0.06). Also, there was significantly more MaD regarding PTV coverage (67% vs 37%, p=0.001), and the heart volume receiving 40 Gy (11.4% vs. 2.1%, p=0.02). The median OS was significantly higher in the PP + MiD group than in the MaD group (42 months vs. 18.4 months; HR = 1.66 [CI95%, 1.12 - 2.47]; p=0.01). When patients with MaD were excluded, median PFS was not statistically different between patients in the dose escalated arm and patients in the standard arm (12 months vs. 16.4 months; HR = 1.35 [CI95%, 0.82-2.23]; p=0.2). Patients with MaD experienced more acute toxicities, especially radiation pneumonitis (p=0.04), and significantly more non-hematological late toxicities (p=0.027). Overall survival of patients depending on the protocol deviations OC-0108 Impact of the Radiation Therapy Quality Assurance in the phase II/III CONCORDE trial.