Background: Current methods for detecting TMPRSS2-ERG fusion transcript in the urine of patients with suspected prostate cancer lack diagnostic sensitivity. We combined urine and prostate biopsy rinse material (BRM) assays to improve the fusion gene detection rate.
Methods: Eighty patients with clinical and/or prostate-specific antigen suspicion of prostate cancer were prospectively included in the study. Urine samples were collected before and after prostate biopsy, and BRM was collected from the biopsy needle. We used reverse-transcription PCR (RT-PCR) for the detection of fusion transcripts. Microfocal cancer (MFC) on biopsy was defined by a single core involved with ≤3 mm of cancer with Gleason score 3 + 3. We statistically assessed the association between RT-PCR and biopsy results.
Results: Urine alone, BRM alone, and both samples were obtained in 4, 19, and 57 patients, respectively. Three patients were excluded because of insufficient material. In the remaining 77 patients, cancer was detected on biopsy in 42 (55%). The diagnostic sensitivity of the assay for cancer detection was 62% (95% CI 47%-78%), 69% (53%-85%), and 89% (73%-99%) with BRM alone, urine alone, and paired samples, respectively. The lowest values were obtained with the urine assay in patients with MFC or Gleason score >3 + 3 cancer. Assays of paired samples provided increased diagnostic sensitivity in all subgroups of patients.
Conclusions: TMPRSS2-ERG fusion gene detection may be improved by performing assays in both urine and BRM. Insufficient cell numbers in urine samples and cell lysis during centrifugation may explain the low diagnostic sensitivity of the urine assay.
© 2012 American Association for Clinical Chemistry