ESTRO 2022 - Abstract Book

S1114

Abstract book

ESTRO 2022

predictor of response (AUC 0.907, 77.7% sensitivity, 92.31% specificity, 91% accuracy). For the 74 operated patients, pathological response was best predicted by Skewness (SSF-2) (AUC = 0.721, 66.6% sensitivity , 73% specificity and 70.89% accuracy) on pretreatment scans. While kurtosis (SSF-6) was the best predictor of pathological response on post-treatment MRI scans. (AUC 0.663, 81.4% sensitivity , 46.15% specificity, 58.23% accuracy). Conclusion Tumor radiomics predicted for response to NACTRT with a fair degree of accuracy. These results need to be further validated in prospectively conducted studies including a larger cohort of patients, if clinical decisions are to be guided by radiomics in future.

PO-1319 Neoadjuvant RT dose escalation for LARC in the new era of radiotherapy; a review of literature

D. Delishaj 1 , S. Ursino 2 , I.C. Fumagalli 3 , A. Cristaudo 4 , A. Cocchi 1 , A. Stefanelli 5 , C.P. Soatti 6

1 ASST Lecco, Department of Radiation Oncology, Lecco, Italy; 2 Azienda Ospedaliero Universitaria Pisana, Department of Radiation Oncology, pisa, Italy; 3 San Donato Hospital, Radiation Oncology Department, San Donato Milanese, Italy; 4 Royal Preston Hospital, Lancashire Teaching Hospital- NHS Tust, Radiation oncology department, Preston, United Kingdom; 5 Azienda Ospedaliero-Universitaria di Ferrara, Department of Radiotherapy,, Ferrara, Italy; 6 ASST Lecco, Department of Radiotherapy, Lecco, Italy Purpose or Objective To analyze the role of neoadjuvant radiotherapy dose escalation for LARC using innovative radiotherapy techniques. Materials and Methods In December 2020 we conducted a comprehensive literature search of the following electronic databases: PubMed, Web of Science, Scopus and Cochrane library. The limit period of research included articles published from January 2009 to December 2020.Screening by title and abstract was carried out to identifying only studies using radiation doses EQD2 ≥ 54 Gy and VMAT, IMRT or IGRT techniques. The authors’ searches generated a total of 2287 results and, according to PRISMA Group (2009) screening process, 21 publications fulfil selection criteria and were included for the review. Results The main radiotherapy technique used consisted in VMAT and IGRT modality (74.12 %). The mainly dose prescription was 55 Gy to high risk volume and 45 Gy as prophylactic volume in 25 fractions given with SIB technique (42.85 %).The mean pCR was 28,2 % with no correlation between dose prescribed and response rates (P = >0.5). The R0 margins and sphincter preservation rate were 98.88 % and 76.03, respectively. After a mean follow-up of 35 months local control was 92,29 %. A ≥ G3 toxicity was 11,06 % with no correlation between dose prescription and toxicities. Patients receiving EQD2 dose > 58.9 Gy and BED > 70.7 Gy had higher surgical complications rates compared to other group (p-value= 0.047). Conclusion Dose escalation neoadjuvant radiotherapy using innovative techniques is safe for LARC achieving higher rates of pCR. EQD2 doses > 58,9 Gy is associated with higher rate of surgical complications. 1 University Hospital of Besançon, Radiation Oncology, Besançon, France; 2 Réseau Hospitalier Neuchatelois, Radiation Oncology, La Chaux-de-Fonds , Switzerland; 3 Hopital Nord-Franche Comté, Radiation Oncology, Montbéliard, France; 4 Centre Hospitalier de Mulhouse, Radiation Oncology, Mulhouse, France; 5 University Hospital of Besançon, Medical Oncology, Besançon, France Purpose or Objective The management of metastatic squamous cell carcinoma of the anus (SCCA) is based on systemic chemotherapy. Recently, docetaxel, cisplatin and 5-Fluorouracil (DCF) was defined as a new option in patients with advanced SCCA with an objective response rate of 88%. The role of a complementary pelvic chemoradiation (CRT) is unknown in this setting. In this study, we reported the safety and efficacy of local CRT in patients with synchronous metastatic SCCA with an objective response after upfront DCF. Materials and Methods Patients with advanced SCCA treated with either standard DCF regimen (sDCF, docetaxel 75 mg/m ² on day 1, cisplatin 75 mg/m ² on day 1, and 5-Fluorouracile (5FU) 750 mg/m ² by 24 hours continuous infusion for 5 days, every 21 days) or modified DCF regimen (mDCF, docetaxel 40 mg/m ² on day 1, cisplatin 40 mg/m ² on day 1, and 5FU 1200 mg/m ² per day for 2 days, every 14 days), followed by pelvic CRT were included. Concurrent chemotherapy was based on mitomycin (MMC) (10 mg/m ² for two cycles) and fluoropyrimidine (capecitabine 825 mg/m ² twice a day at each RT treatment day or two cycles of intra- venous 5FU 1000 mg/m ² from day 1 to day 4). Results From 2013 to 2018, 16 patients received DCF followed by a complementary pelvic CRT for advanced SCCA. The median number of DCF cycles was 6 for sDCF and 8 for mDCF. All patients received the complete radiation dose. RT had to be PO-1320 Pelvic chemoradiation after chemotherapy in patients with advanced anal squamous cell carcinoma J. Boustani 1,1 , A. Grave 1 , B. De Bari 2 , P. Mandy 1 , F. Boulbair 3 , S. Benhmida 1 , M. Noirclerc 4 , P. Monasterolo 1 , S. Kim 5 , C. Borg 5