ESTRO 2021 Abstract Book

S997

ESTRO 2021

1 Liverpool Hospital, Cancer Therapy Centre, Liverpool, Australia; 2 University of New South Wales, South Western Sydney Clinical School, Liverpool, Australia; 3 Ingham Institute for Applied Medical Research, Ingham Institute for Applied Medical Research, Liverpool, Australia; 4 Wollongong Hospital, Illawarra Cancer Care Centre, Wollongong, Australia; 5 Blacktown Hospital, Blacktown Cancer and Haematology Centre, Blacktown, Australia Purpose or Objective There are limited data on survival prediction models in contemporary inoperable non-small cell lung cancer (NSCLC) patients. The objective of this study was to develop and validate survival prediction models in a cohort of inoperable stage I-III NSCLC patients and in a cohort treated with radiotherapy. Materials and Methods Data from inoperable stage I-III NSCLC patients diagnosed from 1/1/2016-31/12/2017 were collected from three radiation oncology clinics. Patient, tumour and treatment-related variables were selected for model inclusion using univariate and multivariate analysis. Cox proportional hazards regression was used to develop a 2-year survival prediction model in one clinic (n=157) and validated in the other clinics (n=155). The South West Sydney Model (SWSM) was developed in the overall population and the Radiotherapy South West Sydney Model (R-SWSM) was developed in patients who received radiotherapy. Model performance, assessed internally and on two independent datasets, was expressed as Harrell’s concordance index(c-index). Results On multivariate analysis, variables predictive of survival in SWSM were DLCO, T stage and treatment intent and in R-SWSM were overall stage, tumour lobe and treatment intent. The SWSM and R-SWSM yielded c- indexes respectively of 0.65 and 0.66 on internal validation and 0.65-0.71 and 0.64-0.65 on external validation. Survival probability could be stratified into three groups using a risk score derived from the models. In the development cohort, 2 year survival with SWSM was 64% in group 1, 62% in group 2 and 25% in group 3 (p<0.05) and for R-SWSM was 71% in group 1, 59% in group 2 and 25% in group 3 (p<0.05). Conclusion Two models with moderate discrimination of 2-year survival were developed. Novel variables included in the models were tumour lobe and treatment intent. Further validation is needed in a larger patient cohort. PO-1201 Importance of coronary calcium score in patients with locally advanced non-small cell lung cancer A. Olloni 1 , A. Olloni 2 , A. Diederichsen 3,4 , O. Hansen 1,5 , C. Brink 6,4 , T. Schytte 7,5 1 Odense University Hospital , Department of Oncology, Odense , Denmark; 2 University of Southern Denmark, Department of Clinical Research , Odense, Denmark; 3 Odense University Hospital , Department of Cardiology , Odense , Denmark; 4 University of Southern Denmark, Department of Clinical Research , Odense , Denmark; 5 University of Southern Denmark , Department of Clinical Research , Odense , Denmark; 6 Odense University Hospital , Laboratory of Radiation Physics, Department of Oncology , Odense , Denmark; 7 Odense University Hospital, Department of Oncology, Odense , Denmark Purpose or Objective Definitive (chemo-) radiotherapy (RT) is the standard of care for patients with locally advanced non-small cell lung cancer (LA-NSCLC). There is emerging evidence that irradiation of the heart can lead to heart disease. Coronary calcium score (CAC) is a reliable marker of subclinical coronary heart disease and an important prognostic marker, and a CAC score higher than 400 may be considered equivalent to prior myocardial infarction. This study aims to perform a CAC score on planning CT scan and evaluate if a high score (above 400) has an impact on the overall survival in patients with LA-NSCLC, thus identifying patients at risk before RT treatment. Materials and Methods The cohort consists of all LA-NSCLC patients treated in 2014-2015 with definitive RT (60-66 Gy/ 30-33 fractions) at the Department of Oncology, Odense University Hospital. Concomitant chemotherapy was received by 80% of the patients. Tumor stage, treatment dose, smoking history, and performance status (PS) were registered prospectively. The CAC scoring was performed retrospectively on planning CT scans during October 2020. The Agatston method was used to measure CAC score in the main coronary arteries (left main, left anterior descending, circumflex artery, and right coronary artery). The patients were divided into two groups; group A: with a CAC score < 400, and group B: with a CAC score ≥ 400. Survival between the two groups was studied using a multivariable Cox model. Results In this study, 138 patients were included. Patient characteristics are shown in table 1. The median CAC score was 40. 102 had CAC score < 400, while 36 had ≥ 400. The 5-year overall survival was 29% (95% CI 21-36), and the mean survival 27 months. Patients with CAC score < 400 had a border significant better 1- and 5-year survival (80% (95% CI 71-86) and 33% (95% CI 24-42), versus 64% (95% CI 46-77) and 16% (95% CI 6-30), p-value= 0.057). When performing backward multivariable Cox analysis, including other clinical factors (tumor stage, treatment dose, age, sex, smoking history, PS and previous heart disease) the patient age and PS showed to be significant variables. Inclusion of these variables in a multivariable Cox model resulted in a non-significant survival impact of CAC score ≥ 400, yielding an HR of 1.22 (95% CI 0.77-1.93).