Multiparametric magnetic resonance imaging of the prostate (mpMRI) is characterized by a significant variability of the positive predictive value for the detection of clinically significant prostate cancer (csPCa). However, there is still a lack of evidence supporting any reliable follow-up strategy in men with a positive mpMRI and a subsequent negative targeted biopsy (TBx). We aimed at providing useful clinical tools to help urologist in identifying men that might benefit from a repeat biopsy (Bx).
313 men with a clinical suspicion of PCa and a positive mpMRI (PI-RADS≥3) with concomitant negative systematic and targeted Bx performed at a single Centre. All patients were then followed with serial PSA measurements, digital rectal examination and eventual follow-up mpMRI and/or repeat Bx. The study outcome was to evaluate the optimal follow-up strategy and identify those with the lowest risk to harbor csPCa missed at previous Bx. We evaluated PSA density (PSAd) and follow-up mpMRI in predicting the presence of csPCa (defined as Gleason score at Bx≥3+4) over time among those who received a follow-up Bx. Secondary outcome was the rate of negative follow-up mpMRI. Kaplan Meier analysis was used to assess csPCa diagnosis-free survival.
Median follow-up was 31 months (IQR: 23-43). During the study period 116 (37%) and 68 (22%) of men received a follow-up mpMRI and a follow-up Bx, respectively. 51 (16%) and 15 (5%) of men had a positive mpMRI and csPCa diagnosis during follow-up, respectively. Among 68 men who received a follow-up Bx, the 2- and 3-yrs csPCa diagnosis-free survival in men with negative vs positive follow-up mpMRI was 97% vs 65% and 92% vs 65%, respectively (HR: 5.7, p=0.01). Differently, the 2- and 3-yrs csPCa diagnosis-free survival in men with PSAd<0.15 vs ≥0.15 was 89% vs 77%, and 86% vs 66%, respectively (HR: 2.6, p=0.12). The combination of negative mpMRI and PSAd<0.15 furtherly reduced the rates of positive follow-up Bx (HR:9.9, p<0.001) (Figure 1a-c). In these men, the rate of csPCa detected at follow-up biopsy was only 6% at 3yrs.
After a negative TBx for a positive mpMRI, more than 40% of follow-up mpMRI were negative. A follow-up mpMRI should be performed to decide on whether to repeat a biopsy. The risk of csPCa diagnosis in men with negative mpMRI and low PSAd is negligible.