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Clinical Article
Prediction of treatment response to neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer by interpretable model based on multiparametric MRI
LI Xuemeng  ZHOU Yanfei  WANG Aoyang  ZHAO Min  WANG Jing  JIANG Li  WEI Wei  GAO Fei 

DOI:10.12015/issn.1674-8034.2026.01.009.


[Abstract] Objective To establish a prediction model based on multiparametric MRI radiomics and clinical-radiology features, and evaluate its efficacy in predicting neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer. The Shapley algorithm was employed to enhance model interpretability.Materials and Methods A retrospective analysis was conducted on 172 patients who received nCRT and surgery from the First Affiliated Hospital of the University of Science and Technology of China (center 1) and the Hefei Cancer Hospital of the Chinese Academy of Sciences (center 2), and Clinical and MRI data were analyzed. According to the 8th edition AJCC tumor regression grading (TRG) criteria for rectal cancer, patients with TRG 0-1 were classified as good responders (GR), while those with TRG 2-3 were classified as poor responders (PR) based on postoperative pathological results. The GR group comprised 77 patients, and the PR group comprised 95 patients. Patients from center 1 were randomly divided into a training set (n = 92) and an internal validation set (n = 40), while the patients from center 2 were utilized as an independent external validation set (n = 40). High-resolution axial T2WI, diffusion-weighted imaging (DWI) and sagittal contrast-enhanced T1WI (CE-T1WI) sequences were selected to delineate the region of interest (ROI) along the tumor margins. PyRadiomics software was used to extract all radiomics features after image preprocessing. Spearman correlation analysis and least absolute shrinkage and selection operator (LASSO) analysis were used to retain the radiomics features strongly associated with the efficacy of nCRT. T2WI, DWI, CE-T1WI and multiparametric radiomics score (Rad-score) were obtained by eXtreme gradient boosting (XGBoost) classifier. The independent clinical-radiology predictors were screened by single-multiple logistic regression to build the clinical-radiology model, and the multiparametric model Rad-score combined with independent clinical-radiology predictors was selected to build the nomogram model. The performance of the model was evaluated using receiver operating characteristic (ROC) curves. The best-performing radiomics model was explained by the Shapley algorithm.Results Univariate and multivariate logistic regression analysis identified age, tumor longest diameter, and neoadjuvant treatment modalities as independent predictors for treatment efficacy. The clinical-radiology model demonstrated the area under the curve (AUC) of 0.80 (95% CI: 0.75 to 0.85) in the training set, 0.73 (95% CI: 0.68 to 0.78) in the internal validation set, and 0.60 (95% CI: 0.55 to 0.65) in the external validation set. Among radiomics models, the multiparametric radiomics model (T2WI + DWI + CE-T1WI) achieved optimal performance, with AUCs of 0.98 (95% CI: 0.95 to 1.00), 0.95 (95% CI: 0.91 to 0.99), 0.86 (95% CI: 0.81 to 0.91) in the training, internal validation, and external validation sets, respectively. The nomogram model achieved the best predictive performance. The AUC, accuracy, sensitivity, and specificity of the training set of nomogram model were 0.99 (95% CI: 0.97 to 1.00), 98%, 95%, and 98%, respectively. The internal validation sets were 0.98 (95% CI: 0.95 to 1.00), 98%, 98% and 98%, respectively. The external validation sets were 0.88 (95% CI: 0.83 to 0.93), 88%, 87% and 87% respectively. DeLong test indicated that the nomogram model's performance was superior to the clinical model and the radiomics models (P < 0.05). Shapley analysis revealed that wavelet-LHL_glszm_SmallAreaEmphasis in DWI sequence was the most important feature in the radiomics model.Conclusions The nomogram based on multiparametric MRI radiomics and clinical-radiology features may be used as an accurate and non-invasive method to predict the efficacy of nCRT in rectal cancer patients, and the Shapley algorithm can provide interpretability of radiomics model. This nomogram has been validated using an external validation set, suggesting its potential utility of providing important guidance for clinical diagnosis and treatment decision-making.
[Keywords] locally advanced rectal cancer;neoadjuvant chemoradiotherapy;magnetic resonance imaging;multiparametric;radiomics;nomogram;interpretability

LI Xuemeng1   ZHOU Yanfei2   WANG Aoyang3   ZHAO Min3   WANG Jing3   JIANG Li4   WEI Wei5   GAO Fei1, 5*  

1 Graduate School, Bengbu Medical University, Bengbu 233030, China

2 Department of Radiology, Hefei Cancer Hospital, Chinese Academy of Sciences, Hefei 236000, China

3 Graduate School, Wannan Medical College, Wuhu 241000, China

4 Department of Pathology, The People's Hospital of Chizhou, Chizhou 247000, China

5 Department of Radiology, the First Affiliated Hospital of USTC, Anhui Provincial Hospital, Hefei 230001, China

Corresponding author: GAO F, E-mail: 15956912758@163.com

Conflicts of interest   None.

Received  2025-07-10
Accepted  2026-01-06
DOI: 10.12015/issn.1674-8034.2026.01.009
DOI:10.12015/issn.1674-8034.2026.01.009.

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