NEW ORLEANS--Repeat biopsies enhance detection and improve the reliability of Gleason grading in the evaluation of prostate cancer, according to two reports from the American Urological Association annual meeting.
A Memorial-Sloan Kettering study found that re-biopsy substantially improved the accuracy of Gleason grading. The investigators had previously shown a discordance between Gleason grading from prostate needle biopsy specimens versus the actual pathologic grade at radical prostatectomy. "Of most concern is that a substantial proportion of patients with Gleason 6 or less from biopsy actually have Gleason 7 or more," Neil Fleshner, MD, MPH, reported.
The researchers explored the issue in a group of 51 control subjects from their neoadjuvant androgen deprivation protocol who had undergone two separate prostate needle biopsies prior to radical prostatectomy. Their highest Gleason scores were compared with those of a concurrent group of 226 patients who had only one set of biopsies.
In the single-biopsy group, 165 patients had biopsy Gleason grade 6 or less, but 63 of these (38%) had a final pathologic grade of 7 or more. In patients who had two biopsies, 37 had biopsy Gleason grade 6 or less, and only 7 (19%) had a final grade of 7 or more.
They concluded that prostate re-biopsy minimizes the unreliability of biopsy-derived grade and should be considered for patients in whom watchful waiting or nomogram-based therapy is selected.
A separate study from Milan, Italy, suggests that a single biopsy per sextant is insufficient for the majority of prostates evaluated after elevated PSA and normal DRE, and that the number of biopsies should be based on prostate weight. Dr. Luciano Nava and colleagues randomized 120 patients (with PSA over 4 ng/mL and normal DRE) to receive either one, two, or three transrectal ultrasound-guided biopsies per sextant.
The number of cancer diagnoses and positive biopsies was significantly greater in patients having three biopsies per sextant (18 total) vs those having one biopsy per sextant (6 total) or even two (12).
Prostate cancer was detected in 32% of patients in the three-biopsy group, 17% in the two-biopsy group, and 15% in the single-biopsy group. The samples were positive in 31%, 25%, and 22% of patients, respectively.
When prebiopsy PSA, age, and prostate weight were correlated with the diagnosis of cancer via a multivariate analysis, only prostate weight was significantly associated. Based on these results, Dr. Nava suggested that prostates weighing less than 40 g would require 12 biopsies for accurate diagnosis; those weighing more than 40 g would need 18 biopsies.