Introduction

This study was designed to investigate the effectiveness of magnetic resonance imaging (MRI) in diagnosing prostate cancer (PCa) before transrectal needle biopsy of the prostate (PBx) for elderly men who were aged 75 years old or older.

Methods

The medical records of 141 elderly patients over the age of 75 years who underwent MRI before PBx at our institutions were reviewed retrospectively. MRI reports were compared with pathological reports. The factors that were used to detect PBx included age, PSA level, lesion size, prostate volume, and PSA density on MRI.

Results

PCa was positive in 103 (73.0%) and negative in 38 (27.0%) patients. Between the PCa-positive and PCa-negative groups, almost all factors except serum PSA level were significant predictors of PCa. MRI-based PSA density was more significant than the others. Of the 38 patients without PCa, 30 cases were not PCa patients on PBx even though they had been judged to be cancer positive on MRI before PBx. The specificity of MRI was 21.1% (8/38). Multivariate logistic regression analysis showed that MRI-based TZ-PSA density was the best independent predictor of PCa. When an MRI-based TZ-PSA density cut-off value of 0.42 was used, sensitivity was 83.5% and specificity was 71.1%. Of the 30 false-positive cases on MRI, PBx might not have been needed in 19 cases considering an MRI-based TZ-PSA density cut-off value of 0.42. We stratified the PCa-positive group according to Gleason score (GS<6, 7, and >8). The accuracy of MRI for detecting PCa was 84.6% (GS<6), 91.7% (GS=7), and 96.7% (GS>8). The cancer detection rate on MRI for high GS PCa was higher than low GS PCa.

Conclusions

These results indicated that MRI before PBx combined with PSA density, especially with MRI-based TZ-PSA density, is helpful to select candidates for PBx. MRI can also detect high GS PCa, so urologists should consider MRI before PBx for elderly men aged 75 years and older with elevated PSA.

Funding

none