Dosiomics and radiomics improve the prediction of post‐radiotherapy neutrophil‐lymphocyte ratio in locally advanced non‐small cell lung cancer

Abstract Purpose To develop and validate a dosiomics and radiomics model based on three‐dimensional (3D) dose distribution map and computed tomography (CT) images for the prediction of the post‐radiotherapy (post‐RT) neutrophil‐to‐lymphocyte ratio (NLR). Methods This work retrospectively collected 242 locally advanced non‐small cell lung cancer (LA‐NSCLC) patients who were treated with definitive radiotherapy from 2012 to 2016. The NLR collected one month after the completion of RT was defined as the primary outcome. Clinical characteristics and two‐dimensional dosimetric factors calculated from the dose‐volume histogram (DVH) were included. A total of 4165 dosiomics and radiomics features were extracted from the 3D dose maps and CT images within five different anatomical regions of interest (ROIs), respectively. Then, a three‐step feature selection method was proposed to progressively filter features from coarse to fine: (i) model‐based ranking according to individual feature's performance, (ii) maximum relevance and minimum redundancy (mRMR), (iii) select from model based on feature importance calculated with an ensemble of several decision trees. The selected feature subsets were utilized to develop the prediction model with GBDT. All patients were divided into a development set and an independent testing set (2:1). Five‐fold cross‐validation was applied to the development set for both feature selection and model training procedure. Finally, a fusion model combining dosiomics, radiomics and clinical features was constructed to further improve the prediction results. The area under receiver operating characteristic curve (ROC) were used to evaluate the model performance. Results The clinical‐based and DVH‐based models showed limited predictive power with AUCs of 0.632 (95% CI: 0.490‐0.773) and 0.634 (95% CI: 0.497‐0.771), respectively, in the independent testing set. The 9 feature‐based dosiomics and 3 feature‐based radiomics models showed improved AUCs of 0.738 (95% CI: 0.628‐0.849) and 0.689 (95% CI: 0.566‐0.813), respectively. The dosiomics & radiomics & clinical fusion model further improved the model's generalization ability with an AUC of 0.765 (95% CI: 0.656‐0.874). Conclusions Dosiomics and radiomics can benefit the prediction of post‐RT NLR of LA‐NSCLC patients. This can provide a reference for evaluating radiotherapy‐related inflammation.