ESTRO 2022 - Abstract Book

S1050

Abstract book

ESTRO 2022

Our long term results show SABR is an effective treatment for early stage NSCLC with excellent overall survival and recurrence rates comparable to other series. Our study found dosimetric variables influencing survival which may need further exploration and may have clinical relevance.

PO-1243 SABR To Primary Tumor In Oligo-M Nsclc Patients: Good News For A New Standard Of Care!

F. Arcidiacono 1 , P. Anselmo 1 , M. Casale 1 , M. Italiani 1 , S. Terenzi 1 , A. Di Marzo 1 , S. Fabiani 1 , L. Draghini 1 , M. Muti 1 , E. Maranzano 1 , F. Trippa 1

1 Radiotherapy Oncology Centre, Oncology, Terni, Italy

Purpose or Objective Stereotactic Ablative Radiotherapy (SABR) has shown high rates of local control and prolonged survival in early-stage non- small cell lung cancer (NSCLC), though its role in oligometastatic disease is undefined. This study aimed to evaluate SABR as a local consolidative therapy in oligometastatic (oligoM) NSCLC patients. Materials and Methods In this prospective trial, we sought to evaluate SABR to primary locally advanced (LA) tumor and metastatic sites in oligoM NSCLC patients. Fit patients received initial systemic therapy according to international guidelines. Patients without progression after front-line therapy (chemotherapy, immunotherapy and targeted therapy) were evaluated by an 18F-FDG- PET/CT to receive consolidative SABR to the primary and all metastatic sites ( ≤ five lesions). Results Between May 2018 and February 2021, 17 oligoM NSCLC were included. Median age was 71 years (range,38-85), 14 (82%) were male and 10 (59%) had adenocarcinoma histology. The main site of metastasis was bone, adrenal gland and brain in 7 (41%), 4 (23%) and 3 (18%) patients, respectively. 15 (88%) patients received systemic front-line therapy: chemotherapy in 8 (47%), immunotherapy in 4 (23%) and a tyrosine kinase inhibitor in 2 (12%). The median administered dose to primary LA tumor was 45 Gy (range,35-50) in 5 fractions. Median follow-up achieved 16 months (range, 6-37). 3 (18%) and 7 (41%) patients developed local relapse and distant metastasis after a median time of 14 months (range,9-15) and 4 months (range,3-6), respectively. No adverse events of ≥ G3 was recorded. At las follow-up 16 (94%) patients are alive, only 5 (33%) discontinued first front-line therapy and started second-line therapy. Conclusion The use of SABR on primary LA tumor in oligoM NSCLC patients was well tolerated and showed favorable clinical outcomes regarding second line therapy-free survival and overall survival. Also considering the results of other prospective trials, SABR to primary LA tumor should be included as standard of care in oligoM NSCLC patients.

PO-1244 Stereotactic Ablative Radiotherapy In Locally-Advanced Non-Small-Cell Lung Cancer: A Phase Ii Trial

F. Arcidiacono 1 , P. Anselmo 1 , M. Casale 1 , M. Italiani 1 , A. Di Marzo 1 , S. Terenzi 1 , L. Draghini 1 , M. Muti 1 , S. Fabiani 1 , E. Maranzano 1 , F. Trippa 1

1 Radiotherapy Oncology Centre, Oncology, Terni, Italy

Purpose or Objective To assess local control (LC) and safety of stereotactic ablative radiotherapy (SABR) in unresectable locally advanced non- small cell lung cancer (LA-NSCLC) patients enrolled in a phase II trial. Materials and Methods All patients were unfit for concurrent chemo-radiotherapy (ChT-cRT). Neoadjuvant ChT was prescribed only in fit patients. The tumor volume included primary tumor (T) and CT-PET positive node/s (N). A simultaneous integrated boost (SIB) was optimized to differentiate the dose for primary tumor (T) and lymph-node/s (N). Results 73 LA-NSCLC patients were recruited. The median age was 73 years (range,45-89) and 51 (70%) were male. Histology was adenocarcinoma (ADK) and squamous cell carcinoma (SCC) in 56% and 44%, respectively. The stage was IIB, IIA, IIIB and oligometastatic IV in 12 (16%), 34 (47%), 18 (25%) and 9 (12%), respectively. 60 (82%) had ultra-central tumor with PTV overlapping the major airways. 43 (59%) received neoadjuvant ChT and 10 (14%) adjuvant Durvalumab. In 35 (48%) cases T and N were separately treated using SIB technique to administer a higher dose to T. Median prescribed dose was 45 Gy (range, 35-55) and 40 Gy (35-45) in 5 fractions to T and N, respectively. During a median follow-up of 20 months (range, 4- 71), 20 (20%) patients had experienced local recurrence (LR) at a median time of 16 months (range, 4-30) and 24 had thoracic nodal-recurrence at a median time of 16 months (range, 4-28). 25 (34%) developed distant metastases 13 months after SABR (range, 4-26). At last follow-up, 57 (78%) patients were alive, 27 (37%) without radiological evidence of disease. No patients developed ≥ G3 acute and late toxicities. The treatment compliance was 100%.

Conclusion