Serum Galectin-3 as a complementary biomarker in non-muscle-invasive bladder cancer.

OBJECTIVE: To evaluate serum Galectin-3 levels in patients with non-muscle-invasive bladder cancer (NMIBC) and to investigate their diagnostic performance and ability to discriminate between low-grade and high-grade disease. METHODS: This prospective controlled study included 80 patients with NMIBC (40 low-grade and 40 high-grade) and 40 age-matched healthy controls. Serum Galectin-3 levels were measured using a commercially available ELISA kit prior to transurethral resection of the bladder tumor. Group comparisons were performed using appropriate parametric and non-parametric statistical tests. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis with bootstrap confidence intervals and internal five-fold cross-validation. Associations between serum Galectin-3 levels and bladder cancer diagnosis and high-grade disease were assessed using univariate logistic regression. RESULTS: Serum Galectin-3 levels differed significantly among the study groups, with the highest levels observed in patients with high-grade NMIBC (P < 0.01). No significant difference was observed between the low-grade and control groups. Galectin-3 demonstrated moderate discrimination between patients with NMIBC and healthy controls (AUC = 0.673), whereas discrimination between high-grade and low-grade NMIBC was more pronounced (AUC = 0.777). Higher serum Galectin-3 levels were associated with bladder cancer diagnosis (OR 1.216, 95% CI, 1.003-1.475, P = 0.046) and with high-grade disease (OR 1.493, 95% CI, 1.097-2.033, P = 0.011). CONCLUSION: Serum Galectin-3 appears to be associated primarily with high-grade tumor biology rather than with the presence of NMIBC itself. Although its overall diagnostic performance for detecting NMIBC is moderate, it may serve as a complementary biomarker for discriminating high-grade disease. External validation in larger multicenter cohorts is required before clinical application.