The effect of sampling more cores on the predictive accuracy of pathological grade and tumour distribution in the prostate biopsy

Abstract

The technique for taking prostatic biopsies has received a major evaluation from many departments around the world in terms of the number of cores, site of biopsy, complications, need for local anaesthesia or sedation, etc., and the authors from Charlottesville review their technique. They present data confirming the impression that increasing the number of cores increases diagnostic sensitivity. Authors from Chapel Hill have performed a pilot study into the concept that cyclooxygenase (COX)‐2 inhibitors inhibit tumour growth in prostate cancer, both in vivo and in vitro. In a few patients they found evidence to suggest that COX‐2 inhibitors may be of value in patients with prostate cancer, concluding that a large trial is indicated. Vascular endothelial growth factor (VEGF) is known to be an important angiogenic factor. The authors from Sweden assessed its value as a marker in renal cancer cells. They found it to be present in most such cells, and found that the correlation between VEGF expression and tumour stage and prognosis was valuable in terms of progression of renal cancer. OBJECTIVE To determine if increasing the number of cores at biopsy improves the predictive accuracy of the Gleason score or aids in anticipating the location and volume of prostate tumour. PATIENTS AND METHODS The charts of 75 consecutive patients who underwent radical retropubic prostatectomy for clinical T1–2 adenocarcinoma of the prostate were reviewed retrospectively; 31 patients had a sextant biopsy (group 1) and 44 had ≥ 8 cores taken (group 2). The concordance between biopsy data and final prostatectomy Gleason score, tumour location and volume was determined for each group. RESULTS There were no differences in mean age, prostate‐specific antigen level before biopsy or biopsy Gleason score for the two groups; 58% of group 1 had their final pathological grade changed after prostatectomy, vs 29% of group 2 (P < 0.05). In neither group was there a significant correlation between the percentage of cores positive for tumour and the percentage volume of prostate involved with cancer, or the ability of the biopsy to predict tumour location. CONCLUSION Taking ≥ 8 biopsy cores improved the pathological grading accuracy, which may be valuable in choosing a treatment for the patient with newly diagnosed prostate cancer.