Correlation analysis of serum amyloid A, neutrophil-lymphocyte ratio, platelet-lymphocyte ratio, and systemic immune-inflammation index with neoadjuvant therapy efficacy and prognosis in breast cancer

Background: Previous studies have extensively explored the relationships between the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) with treatment efficacy and prognosis in breast cancer, though the conclusions have been inconsistent. Currently, research on serum amyloid A (SAA) in this context remains limited. This study aims to comprehensively evaluate the association of SAA, NLR, PLR, and SII with treatment response and prognosis in breast cancer, in order to explore which inflammatory marker may have the greatest prognosis value. Patients and methods: We retrospectively analyzed 348 breast cancer patients treated between 2019 and 2021, including 113 patients who received neoadjuvant chemotherapy. Patients were stratified based on levels of inflammatory markers (SAA: 2.06 mg/L; NLR: 2.50; PLR: 162.89; SII: 650.66). The outcomes assessed included pathological complete response (pCR) and objective response rate (ORR) to neoadjuvant therapy, event-free survival (EFS), and overall survival (OS). Statistical analyses were conducted using Log-rank tests, Cox regression, and Logistic regression. Results: Multivariate analysis identified high SAA as an independent correlate of reduced ORR (OR = 0.26, 95%CI: 0.08-0.80, p = 0.021). No inflammatory markers were found to have statistically significant correlates for pCR. For long-term prognosis, both elevated SAA and SII were independently associated with shorter OS (SAA: HR = 2.67, 95%CI: 1.14-6.26, p = 0.024; SII: HR = 2.65, 95%CI: 1.11-6.32, p = 0.028). Subgroup analysis revealed that among HER2+ patients, high SAA was independently correlated with both worse EFS (HR = 2.53, 95%CI: 1.06-6.07, p = 0.037) and OS (HR = 4.68, 95%CI: 1.11-19.70, p = 0.035). While, the independent associations of NLR and PLR with clinical outcomes were lost after adjusting for clinical confounders. Conclusion: SAA appears to be independently associated with both ORR to neoadjuvant therapy and long-term survival outcomes in breast cancer patients, particularly those with HER2+ status, when compared to NLR, PLR, and SII.