Increasing the number of biopsy cores improves the concordance of biopsy Gleason score to prostatectomy Gleason score

Abstract

To evaluate taking more biopsy cores for predicting the radical prostatectomy (RP) Gleason score compared with the biopsy Gleason score, as although random sextant biopsies are the standard for a tissue diagnosis of prostate cancer, and taking more biopsies increases the detection rate, it is uncertain whether taking more cores improves the prediction of the RP Gleason score. We analysed retrospectively 404 patients from three centres (Seattle 162, Washington 107 and Chicago 135) who had RP for prostate cancer. Six, eight or 10 biopsies were taken based on the physician's preference and the patient's characteristics. Before RP, 158 (39%) patients had six, 65 (16%) had eight and 181 (45%) had 10 biopsy cores taken. The accuracy of the Gleason sum of the three groups was 65/158 (41%), 26/65 (40%) and 104/181 (57.5%), respectively (P < 0.004, 10-core vs six-core). However, when comparing the Gleason score separately (i.e. 4 + 3 is not equal to 3 + 4), the accuracy of the three groups was 48/158 (30%), 20/65 (31%), and 95/181 (52.5%), respectively (P < 0.001, 10-core vs six core). Taking more biopsy cores improves the accuracy of the biopsy Gleason score in predicting the final Gleason score at RP; the predictive accuracy of the final Gleason score may be increased from 41% to 58% by increasing the number of biopsies from six to 10.