Role of prostate biopsy schemes in accurate prediction of Gleason scores.

OBJECTIVES

To determine whether improved prostate sampling by the extended biopsy scheme also improves the accuracy of the biopsy Gleason score (bGS). Because most prostate cancer cases are now detected at an early stage with a low prostate-specific antigen level, the bGS may be the most important factor in therapeutic decision-making. Sextant biopsy schemes had poor correlation with prostatectomy Gleason scores. Extended prostate biopsies have replaced the sextant scheme because of the former's greater cancer detection rate.

METHODS

We identified 426 patients whose biopsy and prostatectomy specimens were reviewed at our center. To minimize the effect of stage migration, all patients before 1997 were excluded. Of the 426 included patients, 221 men had undergone sextant biopsy and 205 men extended biopsy before prostatectomy. The rate of grading concordance and the effect of different variables on the concordance rate was determined.

RESULTS

The overall accuracy of the extended and sextant schemes was 68% and 48% (P <0.001), respectively. Upgrading of the bGS was significantly less likely with the extended scheme (17% versus 41%, P <0.001). The sextant biopsy was more likely to be upgraded for a bGS of 6 or less (44% versus 25%, P <0.002) and a bGS of 7 (14% versus 3%, P <0.02). On multivariate analysis, the biopsy scheme was the only independent predictor of accurate Gleason scoring (P <0.001) and age, prostate-specific antigen level, digital rectal examination findings, prostate size, clinical stage, and number of positive cores were not.

CONCLUSIONS

The use of an extended prostate biopsy scheme significantly improves the correlation between the bGS and prostatectomy Gleason score and reduces the risk of upgrading to a worse Gleason group at prostatectomy.