Predicting pathologic response to neoadjuvant chemotherapy in locally advanced gastric cancer: The establishment of a spectral CT-based nomogram from prospective datasets

Background: To establish a spectral CT -based nomogram for predicting early neoadjuvant chemotherapy (NAC) response for locally advanced gastric cancer (LAGC). Methods: This study prospectively recruited 222 cases (177 male and 45 female patients, 9.59 +/- 9.54 years) receiving NAC and radical gastrectomy. Triple enhanced spectral CT scans were performed before NAC initiation. According to post -operative tumor regression grade (TRG), patients were classified into responders (TRG = 0 + 1) or non -responders (TRG = 2 + 3), and split into a primary (156) and validation (66) dataset at 7:3 ratio chronologically. We compared clinicopathological data, follow-up information, iodine concentration (IC), normalized ICs (nICs) in arterial/venous/delayed phases (AP/VP/DP) between responders and non -responders. Independent risk factors of response were screened by multivariable logistic regression and adopted for model construction. Model was visualized by nomograms and its capability was determined through receiver operating characteristic (ROC) curves. Log -rank survival analysis was conducted to explore associations between TRG, nomogram and patients' survival. Results: This work identified Borrmann classification, ICDP, and nICDP were independent risk factors of response outcomes. A spectral CT -based nomogram was built accordingly and achieved an area under the curve (AUC) of 0.797 (0.692-0.879) and 0.741(0.661-0.811) for the primary and validation dataset, respectively, higher than AUC of individual parameters alone. The nomogram was related to disease -free survival in the validation dataset (Hazard ratio (HR): 5.19 [1.18-12.93], P = 0.02). Conclusions: The spectral CT -based nomogram provides an efficient tool for predicting the pathologic response outcomes of GC after NAC and disease -free survival risk stratification.