Repeat Biopsies May Improve the Reliability of Gleason Scores

July 1, 1997

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.

NEW ORLEANS--Repeat biopsies enhance detection and improve the reliabilityof Gleason grading in the evaluation of prostate cancer, according to tworeports from the American Urological Association annual meeting.

A Memorial-Sloan Kettering study found that re-biopsy substantiallyimproved the accuracy of Gleason grading. The investigators had previouslyshown a discordance between Gleason grading from prostate needle biopsyspecimens versus the actual pathologic grade at radical prostatectomy."Of most concern is that a substantial proportion of patients withGleason 6 or less from biopsy actually have Gleason 7 or more," NeilFleshner, MD, MPH, reported.

The researchers explored the issue in a group of 51 control subjectsfrom their neoadjuvant androgen deprivation protocol who had undergonetwo separate prostate needle biopsies prior to radical prostatectomy. Theirhighest Gleason scores were compared with those of a concurrent group of226 patients who had only one set of biopsies.

In the single-biopsy group, 165 patients had biopsy Gleason grade 6or 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 ofbiopsy-derived grade and should be considered for patients in whom watchfulwaiting or nomogram-based therapy is selected.

A separate study from Milan, Italy, suggests that a single biopsy persextant is insufficient for the majority of prostates evaluated after elevatedPSA and normal DRE, and that the number of biopsies should be based onprostate weight. Dr. Luciano Nava and colleagues randomized 120 patients(with PSA over 4 ng/mL and normal DRE) to receive either one, two, or threetransrectal ultrasound-guided biopsies per sextant.

The number of cancer diagnoses and positive biopsies was significantlygreater in patients having three biopsies per sextant (18 total) vs thosehaving one biopsy per sextant (6 total) or even two (12).

Prostate cancer was detected in 32% of patients in the three-biopsygroup, 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 thediagnosis of cancer via a multivariate analysis, only prostate weight wassignificantly associated. Based on these results, Dr. Nava suggested thatprostates weighing less than 40 g would require 12 biopsies for accuratediagnosis; those weighing more than 40 g would need 18 biopsies.