Objectives: To assess atypical cytology as a positive bladder tumour marker and to determine if indexing atypical cytology to nuclear matrix protein-22 (NMP22) can decrease the false-positive results or increase the positive predictive value (PPV).
Patients and methods: In all, 197 patients at risk of bladder cancer were identified as having atypical urine cytology; 126 were incident (screening) cases and 71 were prevalent (monitoring) cases of bladder cancer. All patients with atypical cytology were evaluated using office cystoscopy. All cancers were confirmed histologically and patients had a negative upper tract study within a 1-year interval. The atypical cytology was then indexed with NMP22 values in an effort to decrease the false-positive results.
Results: Atypical cytology detected 17 cancers in the 126 patients who were screened, giving a PPV of 13% (17/126). When stratified by NMP22, using a threshold of >10 U/mL, the PPV increased to 71% (15/21). In the 71 patients who were being monitored, atypical cytology detected 43 cancers, for a PPV of 61% (43/71). When stratified by NMP22 using a threshold of >6 U/mL, the PPV increased to 92% (35/38).
Conclusions: The clinical utility of atypical cytology was significantly increased in both screening and monitoring for bladder cancer when indexed with NMP22 levels.