Objective:

To investigate the specific diagnostic value of the systemic immune–inflammation index (SII) and systemic inflammation response index (SIRI) combined with the prognostic nutritional index (PNI) and tumor markers (CA19–9 and CEA) in the stage diagnosis of pancreatic cancer.

Approach:

• Study Design: Single-center retrospective cohort study enrolling 257 patients with pathologically confirmed pancreatic cancer.
• Data Collection: Clinical and pathological characteristics, along with pretreatment peripheral blood inflammatory, nutritional, and tumor marker data, were collected.
• Analysis: SII, SIRI, and PNI were calculated and compared across tumor stages and degrees of differentiation.
• Diagnostic Performance: Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of individual indicators and multi-marker combined models.

Key Findings:

• Patients with non-early-stage pancreatic cancer had significantly higher levels of SII, SIRI, CA19-9, and CEA (all P < 0.01), while PNI was significantly lower (P < 0.01).
• With advancing TNM stage, SII, SIRI, and tumor marker levels increased (all P < 0.05), whereas PNI decreased (P < 0.05).
• PNI demonstrated the best diagnostic performance for early-stage pancreatic cancer (AUC = 0.78), followed by CA19-9 (AUC = 0.75), SII (AUC = 0.72), and SIRI (AUC = 0.70).
• The combined inflammatory and nutritional model (SII + SIRI + PNI) achieved an AUC of 0.82, significantly superior to any single marker (P < 0.01).
• In CA19-9–negative patients, the combined model still showed good diagnostic value (AUC = 0.85).

Interpretation:

The combination of systemic immune–inflammation indices with nutritional parameters and tumor markers significantly enhances the specificity and accuracy of early-stage pancreatic cancer diagnosis.

Limitations:

• Single-center study may limit generalizability.
• Retrospective design may introduce selection bias.

Conclusion:

This multi-marker strategy provides an important complementary diagnostic approach, particularly in CA19-9–negative patients.