Development and Validation of an Individualized Nomogram to Identify Undifferentiated‐Predominant Mixed‐Type Early Gastric Cancer

OBJECTIVES: Diagnosis of undifferentiated-type-predominant mixed-type early gastric cancer (UM-EGC) remains challenging due to its complex histological features and overlapping characteristics with other gastric cancer types. We aimed to develop a novel nomogram based on clinicopathological and endoscopic features and validate its performance in predicting UM-EGC prior to endoscopic treatment. METHODS: In this retrospective single-center study, 808 patients with early gastric cancer (EGC) who underwent curative endoscopic submucosal dissection were included. Among them, 493 were assigned to the training cohort and 84 to the external validation cohort. Clinicopathological characteristics and endoscopic features were compared between differentiated EGC and UM-EGC using logistic regression analysis. A predictive nomogram was constructed and evaluated. RESULTS: Multivariable regression analysis identified open-type atrophic gastritis (O1-O3) (odds ratio [OR] 0.25, 95% confidence interval [CI] 0.08-0.82), IIb (OR 9.72, 95% CI 3.01-31.35), IIc (OR 7.75, 95% CI 2.81-21.39), discolored lesion (OR 4.12, 95% CI 1.57-10.80), horizontal location at the greater curvature (OR 2.98, 95% CI 1.15-7.75) or anterior wall (OR 2.91, 95% CI 1.26-6.74), and previous H. pylori eradication (OR 0.23, 95% CI 0.09-0.55) as independently associated with UM-EGC. UM-EGC was also more susceptible to metachronous cancer (OR 5.50, 95% CI 1.30-23.21). The nomogram demonstrated good discriminative ability with an area under the receiver operating characteristic curve of 0.83 (95% CI 0.77-0.87) in the training cohort and 0.82 (95% CI 0.69-0.98) in the external validation cohort. CONCLUSION: This nomogram comprising clinicopathological and endoscopic features may assist in the preoperative prediction of UM-EGC risk. TRIAL REGISTRATION: The clinical trial registration number for patient source in this study is ChiCTR1800017117.