Development and validation of nomograms integrating electrolyte, nutritional, and inflammatory indicators to predict survival in advanced esophageal cancer undergoing immunotherapy or radioimmunotherapy.

Background: The advent of immunotherapy has improved the survival of patients with advanced esophageal cancer (EC), yet there remain problems of poor overall prognosis and substantial individual heterogeneity. This study aimed to explore the correlation between pretreatment peripheral blood indicators and prognosis in patients with advanced EC undergoing immunotherapy or radioimmunotherapy, and to develop and validate prognostic nomograms for clinical risk stratification. Methods: This retrospective study enrolled 221 patients with advanced EC who underwent immunotherapy or radioimmunotherapy. Electrolyte, nutritional and inflammatory peripheral blood indicators, as well as clinicopathological indicators, were selected as potential prognostic factors for collection. The Kaplan-Meier analysis was used to generate survival curves, the log-rank test was conducted to compare intergroup survival differences, and subgroup analysis was performed stratified by whether patients received combined radiotherapy. Univariate and multivariate Cox regression analyses were conducted to screen independent prognostic factors for overall survival (OS) and progression-free survival (PFS). Prognostic nomograms for OS and PFS were constructed based on independent prognostic factors, and internal validation was performed using the Bootstrap method for bias correction. The predictive accuracy, discriminative ability, and clinical utility of the nomograms were evaluated via the area under the curve (AUC), concordance index (C-index), calibration curves, and decision curve analysis (DCA). Results: Multivariate Cox regression analysis showed that serum sodium [hazard ratio (HR) =0.920, 95% CI: 0.864-0.980, P=0.01], serum calcium (HR =1.026, 95% CI: 1.010-1.042, P=0.001), T stage (HR =2.883, 95% CI: 1.172-7.090, P=0.02) and systemic immune-inflammation index (SII) (HR =1.001, 95% CI: 1.001-1.001, P=0.01) were independent prognostic factors for OS. Serum sodium (HR =0.946, 95% CI: 0.901-0.993, P=0.03), prognostic nutritional index (PNI) (HR =0.953, 95% CI: 0.922-0.985, P=0.005), age (HR =0.977, 95% CI: 0.957-0.997, P=0.02), and treatment modality (whether combined with radiotherapy, HR =1.449, 95% CI: 1.048-2.004, P=0.03) were independent prognostic factors for PFS. The C-index of the OS nomogram constructed based on the above indicators was 0.667 (95% CI: 0.614-0.721), and the AUC for predicting 1-, 2-, and 3-year OS rates were 0.726, 0.731 and 0.712, respectively. The C-index of the PFS nomogram was 0.610 (95% CI: 0.560-0.660), and the AUC for predicting 3-, 6-, and 9-month PFS rates were 0.618, 0.627 and 0.643, respectively. The calibration curves and DCA results confirmed that both nomograms had ideal predictive accuracy and clinical application value. Conclusions: Pretreatment serum sodium, serum calcium, SII and tumor (T) stage are independent prognostic factors for OS in advanced EC patients undergoing immunotherapy or radioimmunotherapy, and serum sodium, PNI, age and treatment modality (whether combined with radiotherapy) are independent prognostic factors for PFS. The OS and PFS nomogram model constructed based on the aforementioned multi-dimensional and convenient prognostic indicators has good discrimination, accuracy and clinical application value.