Accuracy of prostate needle biopsy in predicting extracapsular tumor extension at radical retropubic prostatectomy: application in selecting patients for nerve-sparing surgery

Abstract

Objectives. To evaluate prostate biopsy outcomes along with other clinical parameters in an effort to define the cancer-specific safety of nerve-sparing surgery. Methods. Sixty-six consecutive men underwent radical retropubic prostatectomy for clinically localized prostate cancer (T1c = 36, T2 = 30). Preoperative prostate needle biopsies were performed on all patients, and radical prostatectomy specimens were processed in their entirety. Our pathologic end point was capsular perforation extending entirely through the prostatic capsule. Each prostatic side was analyzed individually, for a total of 132 specimens. The specimens were further divided into four categories on the basis of biopsy grade (no cancer = 44, low = 20, moderate = 60, high = 8). Additional study variables included preoperative prostate-specific antigen (PSA) and number of positive biopsy cores. Results. Overall, 40 of the 132 specimens had evidence of capsular perforation. Of the 40 capsular perforations, 39 were observed in specimens (sides) that had cancer identified on biopsy. The one specimen with capsular perforation and a negative biopsy result occurred in the setting of high-grade contralateral cancer. PSA, digital rectal examination, and number of positive biopsy cores did not reliably predict capsular perforation. Conclusions. Our findings suggest that in patients with low- and moderate-grade tumors, the neurovascular bundle can be safely preserved on the side without evidence of cancer having obtained at least three biopsy cores. No safe parameters for considering nerve-sparing surgery were observed in the small number of patients with high-grade tumors, or in any specimen with cancer present on biopsy. Other clinical parameters, such as PSA or number of positive cores, did not aid in identifying candidates for nerve-sparing surgery.