ESTRO 2022 - Abstract Book

S895

Abstract book

ESTRO 2022

"P1" and COVID-19 pandemic (January-December 2020) " P2 ". The comparison concerned the use of HRT between the 2 periods. Data analysis was performed using SPSS version 20. Results During the period of this study, we totalized 780 RT requests (breast: n=669; rectum: n=111), of which 407 during "P1" (breast: n=360; rectum: n=47) and 373 during "P2" (breast: n=309; rectum: n=64). The indication of RT was retained for 729 patients (93.5%) (breast: n=631; rectum: n=98). The simulation was canceled in 102 cases (66: P1; 36: P2). A total of 298 and 254 patients with breast cancer and 29 and 46 patients with rectal cancer were included for analysis in P1 and P2 respectively. For breast cancer ,118 patients (40%) were treated with HRT and 178 patients (60%) with standard RT (SRT) during P1 versus 244 patients (96.4%) and 9 patients (3.6%) respectively during P2. The difference was statistically significant (p10 - 3 ). For rectal cancer , 9 patients (32%) were treated with HRT and 19 (68%) with SRT during P1 versus 39 patients (90.6%) and 4 patients (9.4%) respectively during P2. The difference was statistically significant (p10 -3 ). The LTR-T mean delay, for rectal cancer , was 3.2 ± 1.4 months [1-7 months] and 2.2± 1.5 months [0-7] respectively in SRT and HRT. The difference was statistically significant (p=0.02). For breast cancer , the LTR-T mean delay was 4 ± 2.1 months [0-12] and 3.6 ± 2.8 months [0-14] respectively in SRT and HRT. The difference was statistically significant (p=0.042). Conclusion The results of this study show a significant increase in the use of hypo-fractionated regimens in our department. The reduction in the number of RT sessions contributed to the well management of the crisis during the COVID-19 pandemic with a significant improvement in RT delays. C.S. Ortiz Arce 1 , M.A. Souto del Bosque 2 , A. Olmos Guzmán 3 , D. Hernández Hernández 4 , C.A. Trujillo Rodríguez 4 , D. Calderon Mendoza 3 , P.D. Esqueda Guerrero 3 , F.M. Calva Barrera 5 , A. Betancourt Fuentes 5 , M.P. Ramírez De la Paz 3 , G. Cervantes Aguilar 3 , J.G. Celis Quintal 6 , L.R. Nolazco Muñoz 7 1 UMAE N°1, Instituto Mexicano Seguro Social, Radiotherapy, Leon, Mexico; 2 UMAE N°25, Instituto Mexicano del Seguro Social, Radiotherapy, Monterrey, Mexico; 3 UMAE N°1, Instituto Mexicano del Seguro Social, Radiotherapy, León, Mexico; 4 UMAE N°1, Instituto Mexicano del Seguro Social, Internal Medicine, León, Mexico; 5 UMAE N°1, Instituto Mexicano del Seguro Social, Physics Department, León, Mexico; 6 UMAE N°1, Instituto Mexicano del Seguro Social, General Director, León, Mexico; 7 UMAE N°1, Instituto Mexicano del Seguro Social, Medical Director, León, Mexico Purpose or Objective Infections caused by SARS-CoV-2 (COVID-19) have resulted in a pandemic and health emergency; multiple studies with antibiotics and monoclonal antibodies have been used; however, have not been conclusive regarding the benefit. Treatment with radiation therapy (RT) at low doses generates an anti-inflammatory effect, that are effective and safe in reducing the symptoms produced by COVID-19. The present study was carried out with the objective of determine survival in patients treated with Low Doses of Whole Lung Irradiation (LD-WLI) for COVID-19 moderate or severe pneumonia. Materials and Methods In this matched, prospective, comparative cohort study, patients were matched by age, sex and ARDS. We included PCR-confirmed COVID-19 pneumonia patients older than 18 years of age, with confirmed pneumonia by chest tomography. Control group received treatment based on the national protocol for COVID-19 pneumonia, and the intervention group additionally received low doses of radiotherapy to both lungs. After signed informed consent, patients were treated with Varian with 6 MV AP/PA open fields in supine or prone position. Physical planning was performed using diagnostic tomography upon admission, considering the middle of the depth of the thorax as the isocentre. Treatment plans were manually calculated by a medical physicist with a single dose of 1 Gy to both lungs. Results The study was conducted from April 1st to August 30th, 2020. We included 59 patients; 30 were included in the treatment group, and 29 were included in the control group. Mortality among patients in the radiotherapy group was 27.5% compared with 58.6% in the control group (P<0.05). When ARDS severity was analysed, survival among patients with moderate ARDS was significantly better for the radiotherapy group, 100% vs 40%, respectively (P<0.01). Furthermore, there was no difference in survival among patients with severe ARDS (P 0.90), with 22% for the radiotherapy group and 0% for the control group (Fig. 1). PO-1060 Survival Analysis for Whole Lung Radiation in Patients with Acute Respiratory Syndrome for COVID-19