Abstract: The invention refers to a novel molecular biomarker, namely PTPD1, that is markedly increased in human bladder cancers. PTPD1 expression positively correlated with the grading and invasiveness potential of these tumors. PTPD1 can be detected at high levels in exfoliated bladder cells isolated from urine of bladder cancer patients, while no PTPD1 signal was evident in normal exfoliated bladder cells. Thus, PTPD1 detection in urine samples may represent a novel and reliable marker for non-invasive diagnosis of aggressive bladder cancer.