Introduction:

Multiple recent studies have suggested the most sensitive technique for prostate cancer diagnosis consists of combined MRI-targeted fusion and 12-core systematic biopsies. However, increasing the number of cores taken during biopsy has been shown to increase rates of urinary and infectious complications. In this study, we sought to determine if patients with high-risk prostate MRI lesions (PIRADS 5) can safely forego the systematic biopsy in favor of the MRI-targeted biopsy alone.

Methods:

Between 2015 and 2019, patients enrolled in a prospective clinical trial evaluating the use of MRI-targeted fusion biopsy. All patients with MRI visible lesions underwent MRI-targeted and systematic biopsies during the same setting for prostate cancer diagnosis. The highest Gleason Grade(GG) cancer detected by each modality was recorded and stratified by MRI PIRADS v2 score.  All data was collected prospectively as part of a nationally registered clinical trial(NCT00102544).

Results:

In total, 723 men with PIRADS≥2 lesions underwent subsequent prostate biopsy. A total of 51(7.1%), 87(12.0%), 346(47.9%), and 239(33.1%) biopsied men had a lesion with a greatest PIRADS score of 2, 3, 4, and 5, respectively. Of these men, 185(25.6%) were biopsy naïve. Among patients whose greatest lesion was PIRADS 5 (n=239), 226(94.6%) cancer diagnoses were made. Of these, 217(96.0%) were made by MRI-targeted biopsy, as opposed to 194(85.8%) by systematic biopsy. Of the 9 cancers missed by MRI-targeted biopsy, zero were clinically significant (GG≥3). In regard to upgrading events, MRI-targeted biopsy upgraded 39(16.3%) clinically significant cancers which were either missed or graded as clinically insignificant by systematic biopsy. Conversely, systematic biopsy was responsible for upgrading 2(0.8%) patients, both of which were upgrades from GG=2 on MRI-targeted biopsy to GG=3 on systematic biopsy.

Men with PIRADS scores of 2, 3, and 4 had greater rates of clinically significant cancer misses by MRI-targeted biopsy alone. Of these groups, 1(2.0%), 3(3.5%), and 12(3.5%) cases of clinically significant cancer were missed by MRI-targeted biopsy, respectively, and 1(2.0%), 2(2.3%), and 26(7.5%) cases were missed by systematic biopsy, respectively. Combination biopsy of these patients had a greater likelihood of detecting clinically significant cancer than either targeted or systematic biopsy alone.

Conclusion:

For men with PIRADS 5 lesions on prostate MRI, omission of systematic biopsies in favor of MRI-targeted biopsy alone leads to a marginal (<1%) decline in cancer diagnosis.  However, for PIRADS 2-4 lesions, systematic biopsy adds significant diagnostic value and should be considered in combination with MRI-targeted biopsy.

Funding: NIH Intramural Grant