Identifying prostate cancer in men with non-suspicious multi-parametric magnetic resonance imaging of the prostate.

Background: To formulate clinical pathways for identifying clinically significant prostate cancer (csPC) and avoiding insignificant prostate cancer (isPC) in those without suspicious regions of interest on multi-parametric magnetic resonance imaging (mpMRI) of the prostate.

Methods: A retrospective review identified patients with negative mpMRI who underwent subsequent transperineal prostate biopsy across two centres. Patient characteristics and association with biopsy results were evaluated using univariate and multivariate regression analyses.

Results: A total of 144 patients were identified as having negative mpMRI and undergoing subsequent transperineal prostate biopsy; 18% (25/144) of the cohort were found to have csPC. Logistic regression analysis failed to identify statistically significant predictive factors. In this cohort, if all patients with prostate-specific antigen > 3.0 were biopsied the least amount of csPC is missed, at 20% (5/25) however all isPC would be diagnosed. The least amount of isPC is diagnosed with a biopsy threshold of >15% from the European Randomized Study of Screening for Prostate Cancer calculator with 20% (5/25) of isPC diagnoses made however only 10.5% (2/19) csPC would be diagnosed. A biopsy threshold of >5% risk reduces the number of csPC missed to 37% (7/19) however increases isPC diagnoses to 54% (13/24) of the population.

Conclusion: False-negative rates of prostate MRI for csPC are significant within our cohort at 18%. The decision to biopsy should be made in conjunction with a risk profile acceptable by the patient and clinician. The current study demonstrates that there is a need to balance the risk of missing csPC and harm of diagnosing isPC.