Objectives: The objective of this study was to combine urine and prostate biopsy rinse material (BRM) assays to increase sensitivity for fusion gene detection.
Patients and methods: A total of 194 patients with suspicion of prostate cancer were prospectively included. Urine samples were collected before or after prostate biopsy, as well as BRM. RT-qPCR was used for the detection of fusion transcripts. A microfocal cancer on biopsy was defined by a single core involved with less than 3 mm of Gleason score 3 + 3 cancer. The association between RT-qPCR and biopsy results was statistically assessed.
Results: Seven patients were excluded because of insufficient material. Cancer was detected on biopsy in 100 (53%) patients. Urine alone, BRM alone and both samples were obtained in 155, 164 and 132 patients, respectively. In patients with evidence of cancer on biopsy, a fusion transcript was detected in 63, 55 and 73% of the cases on urine alone, BRM alone and paired samples, respectively. Fusion gene detection on BRM was only associated with the amount of cancer on biopsy. Urine fusion score had a larger area under the curve than serum PSA (p = 0.002) and was significantly higher in patients with high Gleason score and significant cancer on biopsy. Assays of paired samples allowed increasing sensitivity in all subgroups of patients.
Conclusions: TMPRSS2-ERG fusion gene detection may be performed both in the urine and BRM to increase sensitivity. However, only T-E urine score was associated with adverse pathological features.