ESTRO 2020 Abstract Book

S543 ESTRO 2020

Material and Methods All patients who received SABR at a large cancer centre in the UK from 01/01/2010 to 31/12/2016 were reviewed. Patients were included if they had pre-SABR full pulmonary function tests (PFTS) which include forced expiratory volume in one second (FEV1), FEV1 as a percentage of predicted (%FEV1), forced vital capacity (FVC) and DLCO as a percentage of predicted (%DLCO). Patient and tumour demographics were obtained for each patient from electronic health records. Survival times were calculated and analysed using SPSS statistics. Results 410 patients with complete medical records and pre-SABR PFTs were included in the study. Median follow up was 26.1 months. Patient and cancer demographics are summarised in table 1. Median overall survival for the whole cohort was 29.7 months. %DLCO was found to be associated with worse overall survival (cox regression, p=0.001). Performance status and age were also found to be associated with worse survival (p=0.035 and p<0.001 respectively). Overall survival of patients with %DLCO>50% of was 31.9 month, versus 25 months (log rank p=0.011) for patients with %DLCO <50%.

Health Sciences- Doctoral School of Health Sciences, Pécs, Hungary

Purpose or Objective Lung SABRT (stereotactic ablative body radiotherapy) can be the first choice in the treatment of early stage, node negative non-small cell lung cancer (NSCLC), with the same excellent long-term local control and similar overall survival rates as surgery. Local therapy, like operation or radiotherapy has to be chosen in oligometastatic patients as well, when oligoprogression or de novo oligorecurrence is detected. The number of lung nodules can be 1-3, and the local therapy type is independent of the primary tumour histology. Material and Methods From February 2018 twenty oligometastatic patients were treated with lung SABRT at the Clinic of Oncoradiology, Debrecen. The dose of SABRT could be different, 4x12 Gy or 8x7,5 Gy depending on the localization of the metastatic lesion (central or peripheral). We used dose reduction in few cases, mostly because of the proximity of the chest wall. Ultracentrally localized lesions were excluded. Each treatment plan was based on 4D CT with PET-CT fusion, we determined the internal target volume (ITV) by contouring the gross tumor (GTV) volumes in 3-4 respiratory phases. SABRT treatments started with a day 0. Before treating each fraction a 4D cone-beam CT (CBCT) and a 3D CBCT was made for verification. We analysed the performance state (PS), age, sex of the patients, the time between the development of the primary tumor and the metastatic disease, the localization, number, size of the lesions, the biological effective dose (BED) of the SABRT, the early and late side effects, the local control (morphologic and metabolic changes) and the estimated overall survival. In every 3 months a chest CT, and after 3- 12 months a PET-CT was made for follow up. Results The ECOG PS of the patients was 0-2, age was between 32- 82 years. The most common primary tumor type was NSCLC, colorectal cancer and melanoma malignum. The maximum size of the treated lesions was 4 cm. We irradiated one or two lesions simultaneously. Grade 2-3 acute side effects did not develop. The most common late side effect was asymptomatic lung fibrosis in the treatment area. Other serious adverse effects did not occur. After the first year of follow up stable disease or locally partial response was observed based on the metabolic and morphologic information. New lung or other site metastases were evolved in 4 cases so far. Conclusion Lung SABRT for oligometastatic patients is a well tolerable, effective treatment, which is easily and safely feasible after precise planning. The factors, which most affects local control, are BED and fractional dose based on the literature. Yet, because of the short follow up time, we can only estimate the overall survival, but our local control data corresponds with literature data. PO-1019 Long term outcomes and lung function evolution of primary lung tumors treated with Cyberknife SABR F. Sacino 1 , N. Jansen 1 , C. Mievis 1 , L. Seidel 2 , S. Cucchiaro 1 , P. Coucke 1 1 CHU - Sart Tilman, Radiotherapy department, Liège, Belgium ; 2 CHU - Sart Tilman, Biostatistics- SIME, Liège, Belgium Purpose or Objective To report local control and toxicity including pulmonary function for patients treated with robotic stereotactic body radiotherapy (SBRT) for primary lung tumors. Cox regression models were performed to identify factors influencing local tumor control.

Table 1 Median Age

76 years

Sex

Male 195 (48%) Female 215 (52%)

Performance Status

0 1 2 3

17 (4%)

160 (39%) 195 (48%)

38 ( 9%)

Charlson Comorbidity Score (median)

6

Cancer stage

1a 1b 2a 2b

297 (72%) 99 (24%)

1 (0%) 13 (4%)

Graph 1

Conclusion Poor %DLCO was found to be associated with poor overall survival in this study. Further studies using radiation dosimetry and additional co-morbidity factors are needed to clarify true correlation and post SABR survival. PO-1018 Lung SABRT treatment in oligometastatic patients, a prospective review E. Csiki 1 , M. Simon 1,2 , J. Papp 1,2 , Á. Kovács 1,2 1 University of Debrecen, Clinic of Oncoradiology, Debrecen, Hungary ; 2 University of Pécs, Faculty of