The prognostic value of high-grade prostate cancer pattern on MRI-targeted biopsies: predictors for downgrading and importance of concomitant systematic biopsies.

Purpose: To assess the proportion and risk factors for downgrading and reclassification to favorable disease in patients having high-grade (HG) prostate cancer (PCa) pattern on magnetic resonance imaging (MRI)-targeted-biopsy (TB).

Methods: From a radical prostatectomy (RP) cohort, we included patients with pre-biopsy positive MRI and HG [defined by Grade Group (GG) ≥ 3] PCa on MRI-TB. All patients also underwent concomitant systematic biopsy (SB). The main endpoints were the rates of downgrading to GG2, overall downgrading, favorable disease (pT2 and GG2) on RP specimens, and biochemical recurrence-free-survival (RFS). We studied the correlations between HG on concomitant SB, final pathological outcomes and biochemical RFS curves.

Results: Overall downgrading, downgrading to GG2 disease and favorable disease were noted in 36.2%, 24.1%, and 15.4% respectively. HG on concomitant SB was correlated with pT3-4 disease (p < 0.001), pN1 disease (p < 0.001), positive surgical margins (p = 0.043), PSA recurrence (p = 0.003). In multivariable analysis, the presence of GG4-5 on TB (p = 0.013; OR 0.263) and the presence of HG on concomitant SB (p = 0.010; OR 0.269) were negatively and independently correlated with the risk of downgrading to GG2. The presence of HG on concomitant SB independently predicted RFS with a hazard ratio of 2.173 (p = 0.049; 95% CI 1.005-4.697).

Conclusions: Our data shows that a limited HG restricted to TB can often be associated with a favorable grade in almost a quarter of the cases and downgraded in almost half of the cases. Detailed SB features, mainly the presence of HG on concomitant SB, was associated with a more accurate pathology and oncologic outcomes prediction, pleading for the maintenance of SB in MRI-positive patients.