ESTRO 2023 - Abstract Book

S1043

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ESTRO 2023

F. Tohidinezhad 1 , N. Moni George 1 , A. Angrisani 2 , L. Hendriks 3 , S. Peeters 1 , K. Verhoeven 4 , J. Degens 5 , R. Canters 4 , A. Dekker 1 , A. Traverso 1 , D. De Ruysscher 1 1 Maastricht University Medical Center, Department of Radiation Oncology, Maastricht, The Netherlands; 2 University of Campania Luigi Vanvitelli, Department of Precision Medicine-Radiotherapy Unit, Naples, Italy; 3 Maastricht University Medical Center, Department of Pulmonary Diseases, Maastricht, The Netherlands; 4 Maastricht University Medical Center, Department of Radiation Oncology, Maastricht, The Netherlands; 5 Zuyderland Hospital, Department of Respiratory Medicine, Maastricht, The Netherlands Purpose or Objective Pulmonary function tests (PFTs) are commonly used for quantifying lung impairment before and during the treatment trajectory of non-small cell lung cancer (NSCLC). Limited and contradictory results are available on the prognostic value of the PFTs on post-radiation outcomes. This study investigated the association of the baseline forced expiratory volume in 1 second (FEV1) and carbon monoxide diffusing capacity (DLCO) on the overall survival (OS), infectious pneumonia and radiotherapy or immunotherapy-induced (RT/IMT) pneumonitis after definitive radiotherapy in patients with NSCLC. Materials and Methods Retrospective study was conducted on patients with NSCLC who underwent definitive radiotherapy in the Maastro clinic as a referral center for three hospitals from 2015 to 2022. Statistical analyses: Kaplan-Meier with log-rank test and Cox hazard regression. Variables in multivariate analyses: age, gender, body mass index (BMI), metformin use, substance abuse, history of severe respiratory disorders (i.e. embolism, pneumothorax, atelectasis, fibrosis, etc.), Charlson comorbidity index (CCI), bronchodilator medication, TNM stage, location of primary tumor, histology (adenocarcinoma, squamous or other), history of lung surgery and chemotherapy. Results Among 557 included patients, 303 (54%) were male and mean age was 69.9±8.9 years. 248 (45%), 66 (12%), 200 (36%) and 43 (8%) had stage I, II, III and IV. 199 (36%), 241 (43%), 102 (18%) and 15 (3%) had mild, moderate, severe and very severe FEV1 impairment. While 132 (24%) patients had normal DLCO, 157 (28%), 185 (33%) and 83 (15%) had mild, moderate or severe DLCO reduction. The median OS was 43 months (95% CI:37-50). 65 (12%) patients developed an infectious pneumonia. RT/IMT pneumonitis occurred in 25 (5%) patients. Univariable analyses showed that patients with DLCO<40% had a lower survival rate (P=0.002) and were at higher risk of developing an infectious pneumonia (P=0.007). The cumulative hazard of developing infectious pneumonia in patients with moderate to severe airway obstruction (FEV1 30-79%) was significantly higher than in patients with FEV1 ≥ 80% (P=0.021) (Figure 1). In multivariable analysis, following variables were significant risk factors for mortality: age 71-80 (HR=1.9, 95% CI:1.2-3.1), age 81-89 (HR=2.7, 95% CI:1.5-4.9), FEV1<30% (HR=2.5, 95% CI: 1.3-5.1), DLCO 40-59% (HR=1.5, 95% CI: 1.02-2.2), DLCO<40% (HR=2.1, 95% CI: 1.3-3.3), T4 tumor (HR=1.8, 95% CI: 1.2 2.6), N3 (HR=2.4, 95% CI: 1.6-3.7), lower lobe tumor (HR=1.3, 95% CI: 1.01-1.7) and CCI 10-14 (HR=1.9, 95% CI: 1.03-3.6). BMI, N stage, DLCO, CCI, history of pneumonia and indacaterol use were found to be significant risk factors for infectious pneumonia. RT/IMT pneumonitis was associated with T and N stage, metformin use and history of severe respiratory disorders (Table 1).