Is Confirmatory Biopsy Still Necessary for Active Surveillance of Men With Grade Group 1 Prostate Cancer in the Era of Multiparametric MRI?

PURPOSE

Men diagnosed with prostate cancer (PCa) considering active surveillance (AS) are recommended confirmatory biopsy (CBx). Whether this is necessary in the era of MRI-informed biopsies is questionable.

MATERIALS AND METHODS

We studied men with Grade Group (GG) 1 PCa at diagnostic biopsy (DBx) considering AS who underwent MRI and CBx (systematic + targeted) within 18 months. Outcomes were grade reclassification to GG ≥ 2 and GG ≥ 3 and reclassification to unfavorable intermediate-risk (UIR) disease. Subset analyses were performed for men with (1) MRI before DBx and (2) MRI after DBx.

RESULTS

Five hundred twenty-two men had GG1 PCa at DBx. At CBx, 20% reclassified to GG ≥ 2, 12% to UIR disease, and 5.6% to GG ≥ 3. Of the 306 with positive MRI (Prostate Imaging Reporting and Data System ≥3), 27% reclassified to GG ≥ 2 and 16% to UIR disease; men with negative MRI experienced these outcomes at rates of 9.2% and 5.5%, respectively. There were no differences in reclassification outcomes based on MRI timing (group A vs B), and neither PSA density nor prostate volume added to MRI information. In men with MRI targets, approximately one-third of GG 2 reclassification events were only captured by systematic biopsy core(s).

CONCLUSIONS

Reclassification rates at CBx were high in men with positive MRI, but < 10% for all reclassification outcomes in men with negative MRI (95% CI, 5.8%-14% for GG 2; 95% CI, 2.9%-10% for UIR; 95% CI, 0.8%-5.3% for GG 3). Our data support systematic + targeted CBx for men with positive MRI considering AS, whereas men with GG1 cancer and negative MRI should be able to defer CBx.