ESTRO 2023 - Abstract Book

S118

Saturday 13 May

ESTRO 2023

histological grading was available (HR: 0.75, 95% CI 0.39-1.44, p=0,4). Concerning adjusted covariates, better KPS scores were associated with a better survival in our matched univariate cox regression models. Further, higher histolog-ical grades and TNM-stages were related to a higher mortality risk. Conclusion Using population-based data, we observed an almost equal survival of patients treated with SBRT compared to surgery in stage I and II lung cancer. The availability of histological status might not be decisive in therapy planning. SBRT is comparable to surgery in terms of survival. PD-0157 No changes in pulmonary function by spirometry after Stereotactic Body Radiotherapy in lung lesions A.A.A. Geng Cahuayme 1 , A. Giraldo Marín 2 , M. Ramos Albiac 2 , J. Garre Cristau 2 , E. Recalde Vizcay 2 , J. Giralt López de Sagredo 2 1 Vall d'Hebron University Hospital, Radiation Oncology , Barcelona, Spain; 2 Vall d'Hebron University Hospital, Radiation Oncology, Barcelona, Spain Purpose or Objective To evaluate changes in pulmonary function by spirometry after SBRT in lung lesions treated with radical intention over 2- years follow-up in patients without radiological progression or death. Materials and Methods A single-center, retrospective study was performed in a Spanish tertiary hospital that analyzed pulmonary function after lung SBRT from January 1, 2015, to January 31, 2020. Patients included were ≥ 18 years of age and KPS>70, with primary lung cancer or lung metastases smaller than 5cm. Patients were eligible for radiotherapy on a tumor board if they were considered to be inoperable for medical reasons, or refused to undergo surgery. Patients were excluded from the analysis if they had interstitial lung disease or active lower respiratory infection. All patients included had baseline spirometry and at least 2 spirometries during the follow-up. Mixed-effects model were used to evaluate changes in FEV1, FVC, and DLCO at 3, 6, 12, and 24 months after SBRT. Results Fifty-two lung lesions underwent SBRT. The clinical, demographic, and radiotherapy-related characteristics included in the present study are shown in Table 1. Mixed-model regression analysis was performed to predict changes in values of pulmonary functions tests such as FEV1, FVC, and DLCO which is represented in figure 1. No significant differences were observed during the first year in both liters and the percentage of predicted in FEV1 evolution. A gain of 5.9% [95% CI, 2.3; 9.6 percent (p=0.0014)] was beheld after 24 months post-SBRT. Although, there was no significant difference when FEV1 was analyzed in liters 24 months post SBRT (fig 1A-B). Significant differences were observed with increasing FVC in percentage at 3, 12, and 24 months after SBRT. However, no significant differences were found in FVC evolution according to liters during the first two years post-treatment (fig 1C-D). Finally, no differences were reported when analyzing DLCO evolution according to percentage and ml/min/kPa (fig 1E-F).