Predicting Pathological Complete Response in Esophageal Squamous Cell Carcinoma Using a Multimodal Model Integrating Clinical, Radiomics, and Deep Learning Features

Overview

This multicenter, retrospective cohort study reviews the medical records and CT scans of adults with esophageal squamous cell carcinoma (ESCC) who received neoadjuvant immunotherapy plus chemotherapy before surgery at three hospitals in China. The goal is to develop and validate a computer-assisted model that predicts which patients achieve a pathological complete response (pCR)-meaning no residual tumor is found at surgery-after preoperative treatment. Accurate pCR prediction may help clinicians personalize care and avoid unnecessary treatments in likely non-responders. The study includes 363 patients. For each patient, routinely collected clinical information and preoperative venous-phase chest CT images were analyzed. From CT images, both radiomics features and features learned by a "2.5D" deep learning approach with multiple-instance learning (MIL) were extracted. These were combined with clinical variables to create a multimodal prediction model. Model performance will be evaluated using standard metrics and validated in internal and external cohorts. Patients typically received two cycles of taxane-platinum chemotherapy (paclitaxel with cisplatin or carboplatin) combined with camrelizumab every 2-3 weeks before surgery; CT scans were performed within 14 days prior to starting therapy. Surgery (R0 resection) was performed 6-8 weeks after treatment, and pCR was determined by the postoperative pathology report. This is an observational study; no treatments are assigned by protocol. The study was approved by the Ethics Committee of Nanjing Medical University, with informed consent waived due to the retrospective design.

Design and Setting. Multicenter, retrospective cohort study conducted at three affiliated hospitals in China. A total of 363 consecutive ESCC patients met eligibility criteria and were split into a training cohort (n=107), internal validation cohort (n=45), and two external test cohorts (n=129 and n=82). Population. Inclusion criteria: biopsy-confirmed ESCC; locally advanced disease by AJCC 8th edition (cT1N1-T3N0-3M0) on contrast-enhanced CT; completion of standardized neoadjuvant chemo-immunotherapy; availability of high-quality venous-phase chest CT (slice thickness ≤5 mm) within 14 days before therapy; R0 resection 6-8 weeks post-treatment; and a definitive postoperative pathology report documenting pCR. Key exclusions: non-squamous histology, distant metastasis, synchronous malignancies, poor/no venous-phase imaging, slice thickness \>5 mm, severe artifacts, incomplete tumor visualization, incomplete treatment, or missing endpoints. Neoadjuvant Regimen and Imaging. Patients generally received two cycles of taxane-platinum chemotherapy (paclitaxel plus cisplatin or carboplatin) combined with camrelizumab every 2-3 weeks prior to surgery. CT imaging was standardized to venous-phase contrast with 1-5 mm slices; scans without venous phase or \>5 mm thickness were excluded. Tumor volumes were delineated by two radiologists; disagreements were adjudicated by a senior radiologist, and features were harmonized via resampling and intensity normalization. Feature Extraction and Modeling. The pipeline integrated: (1) clinical variables; (2) conventional CT radiomics features (shape, first-order, GLCM, GLRLM, GLSZM, etc.); and (3) 2.5D deep learning slice embeddings aggregated to the patient level using multiple-instance learning (MIL). The 2.5D approach uses adjacent slices in axial/sagittal/coronal planes with ResNet backbones; attention-based MIL plus histogram/BoW-TF-IDF descriptors summarized slice-level predictions. Feature selection used univariate filters, correlation screening, mRMR, and LASSO before training classifiers (logistic regression, SVM, Random Forest, Extra-Trees, LightGBM). Outcomes and Analysis. Primary outcome: pCR at surgery (yes/no). Secondary outcomes: model performance (AUC, sensitivity, specificity, PPV/NPV, calibration) and clinical utility by decision-curve analysis; disease-free survival by Kaplan-Meier analysis. Ethics. Approved by the Ethics Committee of Nanjing Medical University; informed consent was waived given the retrospective design and use of de-identified data.