Negative Multiparametric Magnetic Resonance Imaging for Prostate Cancer: What's Next?

BACKGROUND: Multiparametric magnetic resonance imaging (mpMRI) of the prostate has excellent sensitivity in detecting clinically significant prostate cancer (csPCa). Nevertheless, the clinical utility of negative mpMRI (nMRI) is less clear.

OBJECTIVE: To assess outcomes of men with nMRI and clinical follow-up after 7 yr of activity at a reference center.

DESIGN, SETTING, AND PARTICIPANTS: All mpMRI performed from January 2010 to May 2015 were reviewed. We selected all patients with nMRI and divided them in group A (naïve patients) and group B (previous negative biopsy). All patients without a diagnosis of PCa had a minimum follow-up of 2 yr and at least two consecutive nMRI. Patients with positive mpMRI were also identified to assess their biopsy outcomes.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: A Kaplan-Meier analysis was performed to assess both any-grade PCa and csPCa diagnosis-free survival probabilities. Univariable and multivariable Cox regression models were fitted to identify predictors of csPCa diagnosis.

RESULTS AND LIMITATIONS: We identified 1545 men with nMRI, and 1255 of them satisfied the inclusion criteria; 659 belonged to group A and 596 to group B. Any-grade PCa and csPCa diagnosis-free survival probabilities after 2 yr of follow-up were 94% and 95%, respectively, in group A; in group B, they were 96%. After 48 mo of follow-up, any-grade PCa diagnosis-free survival probability was 84% in group A and 96% in group B (log rank p<0.001). Diagnosis-free survival probability for csPCa was unchanged after 48 mo of follow-up. On multivariable Cox regression analysis, increasing age (p=0.005) was an independent predictor of lower csPCa diagnosis probability, while increasing prostate-specific antigen (PSA) and PSA density (<0.001) independently predicted higher csPCa diagnosis probability. The prevalence of and positive predictive value for csPCa were 31.6% and 45.5%, respectively. Limitations include limited follow-up and the inability to calculate true csPCa prevalence in the study population.

CONCLUSIONS: mpMRI is highly reliable to exclude csPCa. Nevertheless, systematic biopsy should be recommended even after nMRI, especially in younger patients with high or raising PSA levels.

PATIENT SUMMARY: It is a matter of debate whether patients with negative multiparametric magnetic resonance imaging (mpMRI) of the prostate could obviate the need to perform a systematic biopsy. In this report, we looked at the outcomes of patients with negative mpMRI and midterm clinical follow-up at a reference center. We found mpMRI to be highly reliable to exclude significant prostate cancer; nonetheless, systematic biopsy must still be recommended after negative mpMRI in patients with high clinical suspicion of prostate cancer.