Objectives: Gleason grade from prostate needle biopsy (PNB) specimens is important in guiding therapeutic decision making in patients with localized prostate cancer. Recent data from our institution suggest a significant discordance between Gleason grading from PNB versus the actual pathologic grade at radical prostatectomy (RRP). Of most concern is that a substantial proportion of patients with Gleason score of 6 or less from PNB actually have Gleason score of 7 or more at RRP. Under classic measurement theory, one useful way to improve the reliability of an inherently unreliable test is to repeat it. We investigated this strategy in an effort to reduce undergrading errors.
Methods: The control group of patients (n = 51) from our neoadjuvant androgen deprivation protocol was used as the test (two-biopsy) group in this study. These patients underwent two separate PNBs before RRP. We used the highest Gleason score from the two biopsies in these patients and compared the error rates with a concurrent group of patients treated at our institution (n = 226) who had only one set (single-biopsy group) of prostate biopsies. All pathologic slides were reviewed at our institution. Any PNB grade of 6 or less that was scored as 7 or more on final pathology was considered significant.
Results: Mean age, prostate-specific antigen levels, and stage distribution were not significantly different between these two groups. In the single-biopsy group, 165 patients had PNB Gleason score of 6 or less. Of these patients, 63 (38%) had final pathologic grade of 7 or more. In the two-biopsy group, 37 patients had PNB Gleason score of 6 or less. Of these patients, only 7 (19%) had final pathologic grade of 7 or more (P = 0.04).
Conclusions: Prostate rebiopsy minimizes the inherent unreliability of PNB derived grade and should be considered for patients in whom watchful waiting or nomogram-based therapy has been selected.