Evaluation of double immunocytochemical staining for CK20 and P53 as a potential adjunct to cytology for urothelial cancer diagnosis.

OBJECTIVE: To evaluate double immunocytochemical staining with p53 and CK20, as a tool for improving the accuracy of urinary cytology. The aim of the present study was to clarify the diagnostic significance of the expression of these markers and to investigate the possibility of using this information for better monitoring of bladder cancer patients during follow-up.

MATERIAL AND METHODS: One hundred and twenty-five urine cytology cases were retrieved with corresponding histology from our files. One ThinPrep® smear was available for each of them and dual immunocytological staining for p53 and CK20 was performed. Eleven cases were excluded from the study because of hypocellularity. The material comprised 58 malignant, 36 atypical and 20 negative for malignancy cases. Immunocytochemistry was evaluated by two cytopathologists, blinded to the histological diagnosis or follow-up data. A cut-off threshold of five stained atypical cells, according to the literature, was used for evaluation.

RESULTS: Fifty-two out of 58 malignant cases were positive for at least one of the markers (89.6%). In the atypical and negative groups, 18 (50%) and 5 (25%) cases were positive, respectively. Accuracy parameters evaluation for cytology versus the combination of cytology with immunocytological staining were: sensitivity 73.4% versus 91.1%, specificity 100% versus 74.3%, positive predictive value (PPV) 100% versus 88.9% and negative predictive value (NPV) 62.5% versus 78.8%.

CONCLUSIONS: Double immunocytochemical staining for p53 and CK20 is easy to perform and evaluate and can improve cytology sensitivity. It is helpful in establishing a diagnosis of malignancy and may be used as a triage tool to select patients that require cystoscopy during clinical follow-up.