The Effect of Systemic Immune-Inflammatory Index (SII) and Prognostic Nutritional Index (PNI) in Early Gastric Cancer

Abstract

Background: In recent years, the systemic immune-inflammatory index (SII) and prognostic nutritional index (PNI) have been considered potential predictors of survival outcomes in various solid tumors, including gastric cancer. However, there is a notable lack of research focusing on their prognostic implications specifically in the early stage of gastric cancer. This study aims to investigate the prognostic indicators of early gastric cancer (EGC), including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), SII, PNI, and lymph node metastasis (LNM).

Methods: In this retrospective analysis, we examined 490 patients diagnosed with EGC (pT1Nx). The peripheral blood indices of interest were SII, PNI, PLR, and NLR. The receiver operating characteristic (ROC) curves and the area under the ROC curve (AUC) were used to determine optimal cutoff values and prognostic efficacy for each parameter. Additionally, Kaplan-Meier survival curves and multivariate Cox regression models were utilized to delineate independent prognostic factors.

Results: The optimal cutoff values for SII and PNI were determined as 613.05 and 42.21, respectively. Patients in the low SII (SII-L) group demonstrated significantly higher 5-year Disease-Free Survival (DFS) and Overall Survival (OS) rates of 94.7% and 96.2%, compared to the high SII (SII-H) group (DFS: 78.7%; OS: 81.9%), with both differences proving statistically significant (P < 0.001, P < 0.001). Similarly, patients in the high PNI (PNI-H) group showed superior 5-year DFS (93.3%) and OS rates (95.1%) versus the low PNI (PNI-L) group (DFS: 71.4%; OS: 74.3%), also demonstrating statistical significance (P < 0.001, P < 0.001). Multivariate analysis identified SII, PNI, and LNM as independent prognostic factors for EGC. A combined analysis of SII, PNI, and LNM yielded a C-index of 0.723 (P = 0.008).

Conclusion: SII, PNI, and LNM are effective markers for predicting the survival outcomes of patients undergoing radical gastrectomy for EGC.

Keywords: early gastric cancer; lymph node metastasis; prognosis; prognostic nutritional index; systemic inflammatory response index.

Figure 1

Kaplan-Meier curves illustrating 5-year Disease-Free Survival (DFS) and Overall Survival (OS) comparisons for Prognostic Nutritional Index (PNI) (panels A and B) and Systemic Immune-Inflammation Index (SII) (panels C and D).

Figure 2

Forest plot depicting multivariate Cox proportional hazards regression analysis for postoperative recurrence in patients diagnosed with early gastric cancer.

Figure 3

Receiver operating characteristic (ROC) curves evaluating the predictive value of preoperative SII, PNI, N stage of lymph node metastasis, and their combined use for postoperative prognosis in gastric cancer patients.

Figure 4

Decision curve analysis. The y-axis indicates net benefit, calculated as true benefit (gain) minus false benefit (harm). The gray line denotes the assumption where all patients progress or perish, while black horizontal lines signify the hypothesis of no patient progression or mortality. The x-axis represents threshold probability.

Figure 5

5-year DFS curves comparing PNI-H group versus PNI-L group stratified by age: (A) Elderly group and (B) Non-elderly group. 5-year DFS survival curves comparing high SII-H group versus SII-L groups: (C) Elderly group and (D) Non-elderly group.