MP53-01: Detection of clinically significant prostate cancer in mpMRI visible lesions: Size matters. Results from a large, two-institutional series.

Armando Stabile*, Giorgio Gandaglia, Elio Mazzone, Francesco Barletta, Daniele Robesti, Giuseppe Cirulli, Donato Cannoletta, Francesco Pellegrino, Luigi Nocera, Gabriele Sorce, Mario De Angelis, Carlo Andrea Bravi, Milan, Italy, Alberto Martini, Milano, Italy, Thomas Seisen, Morgan Roupret, Paris, France - Metropolitan, Jeffrey R. Karnes, Rochester, MN, Vito Cucchiara, Milan, Italy, Nicola Fossati, Lugano, Switzerland, Francesco De Cobelli, Antonio Esposito, Giorgio Brembilla, Francesco Montorsi, Alberto Briganti, Milan, Italy

Introduction: The relationship between the size of visible lesions (IL) detected at multiparametric MRI (mpMRI) and the detection of clinically significant prostate cancer (csPCa) is still controversial. We hypothesized that the risk of csPCa at mpMRI targeted biopsy (TBx) increases with volumes of ILs.

Methods: We identified 1,348 patients with positive mpMRI (PI-RADS=3) receiving TBx plus systematic prostate biopsy (SBx) at two tertiary centre between 2013 and 2020. A median of 4 TBx cores and 12 SBx cores were performed. The outcome was the presence of csPCa (defined as Gleason score=3+4) at TBx according to the IL volume (very small =0.2cc; small > 0.2cc and = 0.5cc; medium > 0.5cc and = 2.5cc; large > 2.5cc) and to PI-RADS. A multivariable logistic regression analysis (MVA) assessed the relationship between IL volume and csPCa detection at TBx. An interaction term between IL volume and PI-RADS was used to assess the outcome according to PI-RADS. We tested the interaction between IL volume and number of TBx cores. Covariates included PSA density, number of TBx cores, naïve vs repeat biopsy. Violin plots were used to graphically show the relationships between IL volume and csPCa at TBx according to PI-RADS score.

Results: Median number of TBx cores was 5. Overall, 61% and 46% of men had PCa and csPCa at TBx. Overall, 35%, 45% and 19% had PI-RADS 3, 4, and 5 at mpMRI. The interaction term between IL volume and number of TBx cores was not statistically significant. Figure 1 shows csPCa detection according to IL volume stratified according to PI-RADS. For both PI-RADS 3 and 4, the csPCa detection at TBx was lower for very small ILs as compared to bigger ILs (PI-RADS 3: 12%; PI-RADS 4: 20% - all p<0.001). This was confirmed at MVA, very small ILs (OR 1.96) had significantly ower risk of csPCa compared to larger lesions (p < 0.001).

Conclusions: Very small ILs (=0.2cc) were significantly associated with a lower csPCa detection at TBx regardless of the number of TBx cores. Only 1 out of 5 patients with very small PI-RADS 4 lesions had csPCa. These results should be taken into account when deciding on whether performing a prostate biopsy.

Source of Funding: None.