Midkine Is a Potential Urinary Biomarker for Non-Invasive Detection of Bladder Cancer with Microscopic Hematuria

BACKGROUND: To determine the role of Midkine (MDK) in non-invasive detection of bladder cancer (Bca) and the relationship with Ki67. METHODS: Sixty-five Bca patients and 55 non-Bca patients or healthy volunteers were enrolled and voided urine samples were prospectively obtained on the first day of enrollment. Tissue samples were collected by surgery. MDK and Ki67 expressions were analyzed by immunohistochemistry and Western Blot (WB). Specificity and sensitivity of MDK mRNA testing in the detection of Bca were determined by Receiver Operating Characteristic curve (ROC). The relationship between MDK and Ki67 was also assessed. RESULTS: MDK was overexpressed in Bca tissues than that in the non-cancer tissues. The specificity and sensitivity for MDK mRNA testing in urine in the identification of Bca was 80% and 72.3%. MDK detected 85.7% of high-grade tumors, 87.5% of muscle-invasive tumors and 79.4% of tumors larger than 3 cm in patients without gross hematuria. Microscopic hematuria may even increase the detection rate of Bca by MDK testing. Furthermore, the correlation of MDK and Ki67 was found positive. CONCLUSION: MDK was overexpressed in Bca tissues and positively correlated with Ki67. MDK might be a potential biomarker for the detection of Bca, especially for those without gross hematuria but with microscopic hematuria.