Fetal fibronectin: a new screening-marker for bladder cancer?

Early detection of transitional cell carcinoma (TCC) of the urinary bladder is essential for effective treatment. While several serum markers have been evaluated, none have been widely accepted for practical clinical use. Thus, urinary markers have been introduced and investigated to detect the evidence of bladder cancer. But sensitivity and specificity range around 80% respectively. In a prospective study we evaluated fetal fibronectin in the urine of patients with TCC of the urinary bladder. The positivity of oncofetal fibronectin was measured in morning urine samples by membrane immunoassay. This FFN membrane immunoassay is a qualitative test, a solid-phase immunogold assay. A positive sample will result in a single spot after binding of the oncofetal fibronectin-immunogold complex to the membrane containing a monoclonal antibody specific to oncofetal fibronectin (FDC-6, which specifically recognizes III-CS region). The morning urine samples were collected from patients with TCC before they underwent transurethral resection (n=40, 34 non-invasive and 6 invasive carcinomas) and healthy controls (n=20). Oncofetal fibronectin was investigated in the surgical samples by immunohistochemistry (antibody FDC-6, APAAP technique). We found a positive result for oncofetal fibronectin in 38/40 patients with transitional cell carcinoma of the urinary bladder. Two patients with a small pTaG1-TCC showed negative results. In the urine of healthy controls no positive results were detected. Thus, there is a sensitivity of 95% and a specificity of 100%. The TCC was demonstrated as a source of oncfn. To our knowledge this is the first study showing that patients with an evident TCC have a demonstrable amount of oncofetal fibronectin in the urine. We conclude that a positive result is common in TCC-patients. The sensitivity and specificity of this test seems to be extraordinarily high. Because of the small number of cases further studies are required.