ESTRO 2021 Abstract Book

S182

ESTRO 2021

and P <0.001, respectively) At baseline, 1% reported hemoptysis, 1% had SOB in rest, and 5% had arm or shoulder pain. These complaints did not increase significantly during follow-up, except for arm or shoulder pain that was reported more often (increase from 5% to 8%; P <0.05) at 1 year of follow-up. Conclusion After modern photon-based radiotherapy for lung cancer, patients experienced a short-term increase of problems with swallowing and chest pain. Long-term complaints of coughing, shortness of breath during walking or climbing stairs persisted up to 2 years after treatment.

PH-0273 Chemoradiotherapy for NSCLC patients with a high predicted risk of irradical resection H. van Joolingen 1 , M. Rasing 1 , M. Peters 1 , A. van Lindert 2 , L. de Heer 3 , M. Aarts 4 , J. Verhoeff 1 , P. van Rossum 1 1 University Medical Center Utrecht, Department of Radiation Oncology, Utrecht, The Netherlands; 2 University Medical Center Utrecht, Department of Pulmonology, Utrecht, The Netherlands; 3 University Medical Center Utrecht, Department of Cardiothoracic Surgery, Utrecht, The Netherlands; 4 Netherlands Comprehensive Cancer Organization, Netherlands Cancer Registry, Utrecht, The Netherlands Purpose or Objective Irradical (R1-2) resection of non-small cell lung cancer (NSCLC) is a detrimental prognostic factor. Recently, an internationally validated risk score for pre-treatment prediction of irradical resection was developed by Rasing et al. We hypothesized that chemoradiation therapy (CRT) could serve as an alternative approach in patients with a high predicted risk of an irradical resection and aimed to compare overall survival outcomes between surgery and CRT in those patients. Materials and Methods From the original prediction model development cohort, the patients with a predicted high risk for an irradical resection (Rasing score >4) who underwent surgery for stage IIB-III NSCLC in 2015-2018 in The Netherlands were selected. Additionally, from the Netherlands Cancer Registry, patients who received CRT for stage IIB-III NSCLC in 2015-2018 were selected. The surgery and CRT patient groups were matched using 1:1 nearest- neighbor propensity score matching to correct for imbalances in baseline. The primary endpoint of overall survival (OS) was compared using Kaplan-Meier analysis. Subgroup analyses were performed using interaction terms in Cox regression models. Results A total of 2,582 patients who received CRT and 638 surgery patients were eligible. After matching, 523 well- balanced pairs with a high pre-treatment risk of irradical resection remained. In the surgery group, 409 (78.2%) had a R0 resection and 114 (21.8%) a R1-2 resection. Median OS in the surgery group was 46.3 months, compared to 26.5 months in the CRT group (HR 1.42, 95% CI 1.19-1.69, p<0.001). Surgical patients after a R1-2 resection had a worse survival compared to the total CRT group (median OS 20.3 versus 26.5 months, HR 0.73, 95% CI 0.57-0.94, p=0.016). Subgroup analysis did not yield any significant subgroup differences.