A Prediction Model to Help with Oncologic Mediastinal Evaluation for Radiation: HOMER

Abstract

<b>Rationale:</b> When stereotactic ablative radiotherapy is an option for patients with non-small cell lung cancer (NSCLC), distinguishing between N0, N1, and N2 or N3 (N2|3) disease is important.<b>Objectives:</b> To develop a prediction model for estimating the probability of N0, N1, and N2|3 disease.<b>Methods:</b> Consecutive patients with clinical-radiographic stage T1 to T3, N0 to N3, and M0 NSCLC who underwent endobronchial ultrasound-guided staging from a single center were included. Multivariate ordinal logistic regression analysis was used to predict the presence of N0, N1, or N2|3 disease. Temporal validation used consecutive patients from 3 years later at the same center. External validation used three other hospitals.<b>Measurements and Main Results:</b> In the model development cohort (<i>n</i> = 633), younger age, central location, adenocarcinoma, and higher positron emission tomography-computed tomography nodal stage were associated with a higher probability of having advanced nodal disease. Areas under the receiver operating characteristic curve (AUCs) were 0.84 and 0.86 for predicting N1 or higher (vs. N0) disease and N2|3 (vs. N0 or N1) disease, respectively. Model fit was acceptable (Hosmer-Lemeshow, <i>P</i> = 0.960; Brier score, 0.36). In the temporal validation cohort (<i>n</i> = 473), AUCs were 0.86 and 0.88. Model fit was acceptable (Hosmer-Lemeshow, <i>P</i> = 0.172; Brier score, 0.30). In the external validation cohort (<i>n</i> = 722), AUCs were 0.86 and 0.88 but required calibration (Hosmer-Lemeshow, <i>P</i> < 0.001; Brier score, 0.38). Calibration using the general calibration method resulted in acceptable model fit (Hosmer-Lemeshow, <i>P</i> = 0.094; Brier score, 0.34).<b>Conclusions:</b> This prediction model can estimate the probability of N0, N1, and N2|3 disease in patients with NSCLC. The model has the potential to facilitate decision-making in patients with NSCLC when stereotactic ablative radiotherapy is an option.