Percentage of core lengths involved with prostate cancer: Does it add to the percentage of positive prostate biopsies in predicting postoperative prostate-specific antigen outcome for men with intermediate-risk prostate cancer?

Objectives. To evaluate whether the percentage of core lengths involved with prostate cancer added clinically significant information concerning the time to postoperative prostate-specific antigen (PSA) failure in the intermediate-risk patient beyond what is provided by the percentage of positive biopsies. Methods. Cox regression multivariable analysis was performed to compare the ability of the two measurements of biopsy cancer volume to predict the time to PSA failure from a series of 184 surgically treated intermediate-risk patients. PSA outcome was estimated using the actuarial method of Kaplan and Meier, and comparisons were made using the log-rank test. Results. Both the percentage of core lengths involved with prostate cancer (P = 0.01) and the percentage of positive biopsies (P = 0.002) were significant predictors of the time to PSA failure on univarlable analysis. The 4-year PSA outcome was 83% versus 47% (P = 0.0008) and 83% versus 53% (P = 0.007) for the percentage of positive biopsies stratified by 50% or less versus greater than 50% and the percentage of core lengths involved with prostate cancer stratified by 25% or less versus greater than 25%, respectively. However, only the percentage of positive biopsies remained significant (P = 0.03) on multivariable analysis. Conclusions. The percentage of core lengths involved with prostate cancer did not provide additional clinically relevant information to the percentage of positive biopsies for patients with intermediate-risk prostate cancer. Therefore, the routine measurement of core involvement may not be necessary in this patient population. (C) 2002, Elsevier Science Inc.