High Prevalence of Clinical Understaging in Early Gastric Cancer: An Analysis of the NCDB

This study aimed to identify the incidence of clinical understaging in early gastric cancer (GC) and to identify variables associated with increased risk of a patient being understaged.

Clinical stage I (T1/2 N0) GC patients undergoing oncologic resection without neoadjuvant therapy from 2013 to 2020 were identified in the National Cancer Database (NCDB). Patients found to have a higher stage of cancer on final pathologic review were considered understaged. Clinicopathologic predictors of understaging were identified using multivariable logistic regression. The relationship between identified variables and understaging was modeled using logistic regression with natural cubic splines to allow for a flexible, nonlinear analysis. Cox proportional hazards analysis and Kaplan-Meier curves were used to evaluate survival outcomes.

The study identified 4370 clinical stage I GC patients, 36% of whom were initially understaged on clinical staging. Tumor size per millimeter increase (OR, 1.05; 95% confidence interval CI 1.04-1.05; p < 0.001), higher grade (moderate: OR, 2.76; 95% CI 1.99-3.84; poor/anaplastic status: OR, 5.99; 95% CI 1.99-3.84, p < 0.001), and non-academic treatment facilities (OR, 1.19; 95% CI 1.03-1.38; p = 0.017) were associated with increased risk of understaging. Spline analysis showed increased risk of understaging based on tumor size. This was compounded when tumor differentiation was considered, such that a tumor measuring 2.5 cm was associated with 16.9%, 31.8%, or 51.6% likelihood of clinical understaging if the tumor was well, moderately, or poorly differentiated, respectively. Understaging was associated with increased mortality (OR, 2.31; 95% CI 2.10-2.95; p < 0.001).

More than one third of clinical stage I GC patients are understaged. Tumor grade and size should be considered at preoperative evaluation of early GC to improve identification of patients at risk for understaging.