Limitations of biopsy Gleason grade: implications for counseling patients with biopsy Gleason score 6 prostate cancer

PURPOSE: We examined the implications of underestimating Gleason score by prostate biopsy in patients with biopsy Gleason 6 prostate cancer with respect to adverse pathological findings and biochemical recurrence after radical prostatectomy. MATERIALS AND METHODS: We retrospectively reviewed clinical and pathological data on a cohort of 531 patients with Gleason score 6 on prostate biopsy who underwent radical retropubic prostatectomy between June 1992 and January 2002. Patients were excluded if they received neoadjuvant androgen deprivation. Concordance between biopsy and radical prostatectomy Gleason score was examined. A comparison was made with respect to final radical prostatectomy specimen pathology and the risk of biochemical recurrence between cases that remained Gleason 6 and those with a final grade of 7 or greater. RESULTS: A total of 451 patients were included in the analysis. Mean followup was 55.1 months (range 12 to 123.4). Of the patients 184 (41%) had a Gleason score of 7 or greater after a review of the entire prostate, while 37 (8%) had a score of less than 6 and 230 remained with Gleason 6. Patients who were under graded were more likely to have extraprostatic extension (22% vs 4%, p <0.01), seminal vesicle invasion (9% vs 2%, p <0.01) and biochemical recurrence (10% vs 3%, p <0.01) compared to those who remained with Gleason score 6. CONCLUSIONS: Gleason grade on needle biopsy is an inexact predictor of the final grade following radical prostatectomy. Patients with biopsy Gleason score 6 who are under graded are at significantly higher risk for adverse pathological features and biochemical recurrence than patients who remain with Gleason score 6 or less on final pathology findings.