The extent of biopsy involvement as an independent predictor of extraprostatic extension and surgical margin status in low risk prostate cancer: Implications for treatment selection

Purpose: We identify predictors of extraprostatic extension and positive su rgical margins in patients with low risk, prostate cancer (prostate specifi c antigen [PSA] 10 ng./ml. or less, biopsy Gleason score 7 or less and clin ical stage T1c-2b). Materials and Methods: From August 1997 to January 1999, 143 previously unt reated patients underwent radical retropubic prostatectomy for clinically l ocalized prostate cancer. A total of 62 patients were low risk, with PSA 10 ng./ml. or less, biopsy Gleason score 7 or less and clinical stage T1c-2b, and had sextant biopsy with separate pathological evaluation of each sexta nt cores. PSA, clinical stage, biopsy Gleason score, average percentage of cancer in the entire biopsy specimen, maximum percentage of cancer on the m ost involved core, number of cores involved and bilaterality were evaluated for association with extraprostatic extension, seminal vesicle involvement and positive surgical margins. Results: Of the 62 patients 13 (21%) had extraprostatic extension, 6 (10%) seminal vesicle involvement and 20 (32%) positive surgical margins. Average percentage greater than 10% and maximum percentage greater than 25% were a ssociated with extraprostatic extension (p = 0.01 and 0.004, respectively). Average percentage greater than 10%, maximum percentage greater than 25%, more than 2 cores involved and bilaterality were associated with positive s urgical margins (p = 0.007, 0.01, 0.002 and 0.03, respectively). On multiva riate analysis maximum percentage remained the only independent predictor o f extraprostatic extension (p = 0.03), and the number of cores involved rem ained an independent predictor of positive surgical margins (p = 0.01). Bio psy Gleason score, PSA and clinical stage did not correlate with extraprost atic extension or positive surgical margins in this patient population. Conclusions: In low risk prostate cancer the extent of biopsy involvement s ignificantly correlates with the risk of extraprostatic extension and posit ive surgical margins. Biopsy information should be considered when selectin g and modifying treatment modalities.