Introduction:

The high performance of MRI fusion biopsy in identifying men with clinically significant prostate cancer (csPCA) has fostered the access of this diagnostic technique to a growing number of men undergoing prostate biopsy.  While PI-RADS and other scoring systems are able to accurately stratify MRI findings by risk of csPCa, some patients have negative MRI fusion biopsies despite the presence of “high-risk” lesions on MRI (defined here as the presence of PI-RADS or Likert 4 or 5 lesion). In this study, we aimed to describe detailed clinical follow-up of patients with a high-risk MRI lesion but negative targeted, fusion biopsy. We present subsequent imaging, biopsy and treatment results and evaluate factors associated with subsequent csPCa diagnosis.

Methods:

Retrospective chart review was performed on men who had a negative MRI fusion biopsy, with or without systematic biopsy, due to the presence of a high-risk lesion on MRI. Patient characteristics, biopsy indications, follow up PSA, MRI, biopsy results and subsequent treatment were extracted from the medical record. Univariate statistics were used to evaluate associations between patient characteristics and diagnosis of csPCa, defined as Gleason Grade Group 2 or higher, on follow-up.

Results:

From 2014-2020, 735 patients were biopsied due to a high-risk lesion, among which 106 (14%) were negative. Median age was 66 (IQR 62 to 71). Median PSA was 6.2 (IQR 4.2 to 8.2). Biopsy indications included elevated PSA (80, 75%), active surveillance follow-up (71, 70%), and prior cancer treatment (8, 8%). Median follow-up was 17.4 months (IQR 8.4 to 40.1). Among 30 (28%) men with a follow-up MRI, 7 (23%) were re-classified to PI-RADS 3 or lower. A repeat biopsy was performed in 21 (20%) patients, with the finding of csPCA in 9 (43% - representing 9% of the entire study group), GG1 in 3 (14%), and no cancer in 9 patients (43%). Six (67%) patients with csPCa had a positive targeted biopsy of the original region of interest. Eleven men (10%) underwent subsequent treatment. Among baseline characteristics, only age (p=0.04) was associated with detection of csPCa on follow up.

Conclusion:

Men with a high-risk MRI and negative fusion biopsy may have clinically significant prostate cancer detected on follow-up, though this rate is less than 10% over an intermediate follow-up period. Subsequent MRI and patient age may be useful to help guide management in this patient population.

Funding: N/A