Clinical significance of baseline serum IgG in metastatic renal cell carcinoma patients undergoing cytoreductive nephrectomy.

Abstract

564 Background: This study aimed to explore the association between preoperative serum immunoglobulin G (IgG) levels and inflammation- and coagulation-related markers, including fibrinogen (FIB), C-reactive protein (CRP), and the neutrophil-to-lymphocyte ratio (NLR), in patients with metastatic renal cell carcinoma (mRCC) undergoing cytoreductive nephrectomy. The study further sought to clarify whether humoral immune activation driven by B cells is involved in the inflammatory and coagulation response in RCC, and to determine whether baseline IgG levels may serve as potential biomarkers for therapeutic efficacy and prognosis. Methods: A total of 64 patients with mRCC who underwent cytoreductive nephrectomy and received first-line targeted and immune therapy between January 2019 and September 2025 were retrospectively enrolled. Clinical characteristics and baseline peripheral serum levels of IgG, FIB, CRP, and NLR were collected. The associations between serum IgG and FIB, CRP, and NLR were evaluated using the Wilcoxon rank-sum test and Pearson correlation analysis. Kaplan–Meier survival analysis and Cox proportional hazards regression models were used to assess the relationships between baseline IgG levels and progression-free survival (PFS) as well as overall survival (OS). Results: Patients were divided into two groups according to whether serum IgG exceeded the upper limit of the normal range (8.6–17.4 g/L). The Wilcoxon rank-sum test showed that serum IgG levels were significantly associated with CRP, FIB, and NLR (all P < 0.005). Pearson correlation analysis demonstrated moderate positive correlations between IgG and both FIB (r = 0.525) and CRP (r = 0.428). Kaplan–Meier analysis revealed that patients with elevated IgG had significantly shorter overall survival compared to those with normal IgG levels (P = 0.013), whereas progression-free survival showed no significant difference (P = 0.69). In Cox regression analysis, elevated IgG was significantly associated with worse overall survival (HR = 5.53, 95% CI: 1.22–25.05, P = 0.026), but not with PFS (HR = 1.22, 95% CI: 0.47–3.17, P = 0.69). Conclusions: Elevated baseline serum IgG levels in mRCC patients indicate a pronounced humoral immune response that is closely linked to systemic inflammation and coagulation activation. Increased IgG is significantly associated with inferior overall survival, suggesting that serum IgG may serve as a potential prognostic and predictive biomarker for treatment outcomes in mRCC.