ESTRO 2022 - Abstract Book

S1064

Abstract book

ESTRO 2022

Materials and Methods From Jan 2017 to Dec 2019, we treated 140 consecutive patients with definitive CTRT. All patients were treated with volumetric modulated arc therapy (VMAT)and image guidance was done using once weekly cone bean computed tomography. The need of ART was determined in our routine weekly audit. In patients deemed suitable for ART, replanning was done using four dimensional CT simulation and treated with VMAT. Overall survival (OS) and Progression free survival (PFS) was calculated from the date of diagnosis till the date of death/progression or last follow up, respectively. OS and PFS was calculated using Kaplan-Meier method. Results A total of 35 patients required ART after a median dose of 26 Gy (IQR 14-36 Gy). The median age was 61 years (range, 50 - 65), majority had non-small cell lung cancer. The need for ART was pre-emptively anticipated in approximately 30% patients initiation of treatment. The median pre-ART gross tumor volume (GTV) and planning target volume (PTV) were 153 cc (range, 3.2-1207 cc) and 544 cc (range,203-1659 cc). The median post-ART GTV was 80.8 (range,3.1-566 cc) and PTV was 419 (range, 144-1023 cc). After a median follow up of 27 months, the median OS and PFS was 29 months (95% CI, 22.6-35.8) and 15.1 months (95% CI, 12.3-18), respectively. The 2-year OS and PFS were 65.7% and 36%, respectively. Of 25 patients who progressed, local failure was seen in 15 patients (43%) after a median time of 6.3 months (range, 3.5-45.2 months). Conclusion Patients of lung cancer requiring ART during CTRT had comparable PFS and OS. However, local failures were comparably higher, which suggest careful delineation of target volume at the time of ART is of utmost importance to avoid missing the target. 1 University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio" University of Florence, Florence, Italy; 2 Azienda Ospedaliero-Universitaria Careggi, Department of Radiation Oncology , Florence, Italy; 3 University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio" , Florence, Italy; 4 Erasmus MC Cancer Institute, Department of Radiation Oncology, Rotterdam, The Netherlands Purpose or Objective Oligoprogression (OPD) is defined as a disease’ state where limited progression (1-3 metastases) is observed in patients undergoing systemic treatment. Local treatment of OPD may enable to postpone systemic therapy switch, in particular in patients undergoing novel targeted or immune therapies. In this study we investigated the outcome after stereotactic body radiotherapy (SBRT) in patients with metastatic lung cancer treated with chemo-immunotherapy who were diagnosed with oligoprogression. Materials and Methods Thirty-seven patients, 21 female and 16 male, with metastatic lung cancer and diagnosis of oligoprogression were included and were treated with Cyberknife and Linac SBRT between June 2015 and August 2021. SBRT was delivered to lung (n=18), mediastinal node (n=8), bone (n=5), adrenal gland (n=5) and kidney (n=1). Dose regimens consisted of 30-51 Gy in 3 fractions, 30-55 Gy in 5 fractions, 52.5 Gy in 7 fractions and 44-56 Gy in 8 fractions, resulting in a median BED of 115.5 (range 48-138) Gy10. Dose was expressed as Biological Effective Dose for α / β =10 (BED10). Kaplan-Meyer method was used to calculate Overall Survival (OS), Local Control (LC) and Disease Progression-free Survival (DPFS) from the start date of SBRT to event. Results After a median follow up of 20 months (range 1-48), median overall survival was 26 months (figure 1), and median DPFS was 6 months. LC was 82% at 1 year and 74% at 2 years. Median age was 66 years (range 25–82). All patients were treated with systemic treatment before the start of the SBRT: 9 chemotherapy (CT) alone (24%), 14 CT plus immunotherapy (IT) or plus Tyrosin kinase inhibitors (TKI) (38%) and 14 IT/TKI alone (38%). At univariate analysis, age, type of systemic treatment, and number of chemotherapy lines were not significant prognostic factors for overall survival. PO-1261 Is SBRT an effective treatment in metastatic lung cancer with oligoprogressive disease? M. Aquilano 1 , M. Loi 2 , L. Livi 3 , J. Nuyttens 4