Should all prostate needle biopsy Gleason score 4 + 4 = 8 prostate cancers be high risk? Implications for shared decision-making and patient counselling

Objectives: To estimate the probability of downgrading to Gleason score ≤7 at radical prostatectomy for men with a prostate needle biopsy demonstrating Gleason score 8 (4 + 4).

Methods: This is a retrospective review of men with Gleason score 8 (4 + 4) prostate cancer on needle biopsy who then underwent a radical prostatectomy at the Karmanos Cancer Institute or the University of Michigan. Men with any pattern 5 on the diagnostic biopsy were excluded. The objective was to estimate the proportion of patients whose tumors were downgraded to Gleason score ≤7 at radical prostatectomy and to identify clinical and biopsy parameters associated with downgrading.

Results: Median age of our cohort was 63 years (IQR: 59, 67.5) and median follow-up was 15 months (IQR: 7, 37). Of the 105 men that met inclusion criteria, 59% (62/105) were downgraded to Gleason score ≤7 at radical prostatectomy. Having ≤2 cores demonstrating Gleason score 8, ≤50% maximal tumor involvement of any individual core positive for Gleason score 8, or the presence of Gleason pattern 3 (such as 3 + 4, 4 + 3, or 3 + 3) in other biopsy cores were all independently associated with downgrading in our multivariable model. Depending on the absence, presence, or combination of these 3 factors, patients had an estimated 6% to 82% probability of having their tumor downgraded at radical prostatectomy.

Conclusions: Men with low volume Gleason 8 (4 + 4) and/or the presence Gleason pattern 3 on prostate needle biopsy often have their tumors downgraded at radical prostatectomy. The presence of these preoperative biopsy parameters could affect pretreatment counseling and impact patient management.