Biomarkers for Bladder Cancer: Present Challenges and Recent Developments

Bladder cancer is the most common carcinoma of the urinary system. Early detection and diagnosis of bladder cancer is a major challenge. Urine cytology has low sensitivity and specificity, especially for low-grade tumors. Cystoscopy is the gold standard for the detection and follow-up of bladder tumors. However, it is an expensive and invasive procedure and can fail to detect many bladder lesions such as carcinoma in situ (CIS). It is thus an unmet need to identify a robust set of biomarkers, which can improve the current diagnostic practice. During the last one decade, several bladder tumor markers have been identified for diagnosis, however, none of these diagnostic markers offer sufficient sensitivity and specificity to be routinely used in the clinics. Recent advancement in mass spectrometry (MS)-based quantitative proteomics has emerged as a powerful method to discover wide range of proteins in complex biological samples. In this review, we summarize the status of biomarkers currently identified and used for bladder cancer diagnosis.