This patient was started on finasteride therapy 18 months prior. Fi≠nasteride typically reduces the serum PSA level by approximately half. Using corrected PSA measurements
(ie, doubling PSA level while on finasteride therapy), this patientís current corrected PSA level is
5.6 ng/mL, with a PSA velocity of 1.2 ng/mL per year over the last 3 years. Given these measurements, prostate biopsy is recommended. MRI of the prostate can suggest the location and extent of a tumor; however, biopsy is needed for pathologic diagnosis.