Bladder cancer innervation: Does it affect prognosis?

855 Background: Numerous studies have lately demonstrated the potentially important role of autonomic nerves in tumorigenesis and cancer progression. The association between nerve fiber density and tumor histopathological characteristics and clinical outcome varies across different cancer types. Only scant information on urinary bladder carcinoma innervation are available in the present literature sources. Methods: We analyzed 76 randomly selected cases of urinary bladder transitional cell carcinoma samples acquired by cystoscopy. Diagnoses were made based on WHO 2018 criteria. For detection of nerve fibers and their subtypes, dual indirect immunofluorescence staining was performed using the following antibodies: mouse monoclonal antibody against PGP9.5 (common neuronal marker) and rabbit polyclonal antibodies against tyrosine hydroxylase (TH, sympathetic nerves), vesicular acetylcholine transporter (VAChT, parasympathetic nerves) and calcitonin gene-related peptide (CGRP, sensory nerves). The secondary fluorescent antibodies gave red and green fluorescence, respectively. Nerve fiber density was evaluated using fluorescence microscope with a 40x objective (1 mm 2 surface) and scored semiquantitatively as absent, low (random fibers), medium (one fiber in 1-3 fields), or high (several fibers in one field). Results: The highest innervation density was observed in normal or inflamed mucosa. There was a decreasing innervation density from low-grade noninvasive through high-grade noninvasive to high-grade invasive tumors, with only scant nerve fibers in the latter. In general, most of the fibers contained sympathetic nerve filaments, while parasympathetic nerves were found only rarely and sensory filaments were only scant in few specimens. Virtually no nerve fibers were identified in the papillary stroma of the tumors. Conclusions: The significance of innervation density in the biology of bladder carcinoma remains unclear. Our results indicate that decreased nerve density is related to unfavorable prognosis of the tumor.