Value of p16^INK4a in the diagnosis of low-grade urothelial carcinoma of the urinary bladder in urinary cytology

BACKGROUND: The sensitivity of urinary cytology for the diagnosis of urothelial carcinomas is low, particularly in lowgrade carcinomas. The UroVysion test is a fluorescent in situ hybridization multiprobe assay that increases the sensitivity of urinary cytology. However, this test is not widely available. P16INK4a, a protein involved in cell cycle progression, is overexpressed in urothelial carcinoma. Immunocytochemical expression of p16 INK4a has been examined in biopsy samples from urothelial carcinomas, but few studies have addressed this protein in urine cytology. METHODS: The authors compared the results of p16INK4a immunoreactivity in cytology and biopsy samples from 83 cases, including low-grade urothelial carcinomas, reactive epithelial lesions, and negative cases. RESULTS: p16INK4a assessment of in urine cytology samples showed a sensitivity of 66.7% and a specificity of 82.8% in the diagnosis of low-grade urothelial carcinomas. CONCLUSIONS: On the basis of these results, the authors propose that immunocytochemical detection of p16INK4a is a reliable tool in urine cytology, both for the diagnosis of low-grade urothelial carcinomas and for follow-up purposes. More retrospective and prospective studies are required to verify these results. © 2012 American Cancer Society.