Positive prostate biopsy laterality and implications for staging

Objectives. To examine the effect of including positive prostate biopsy information in palpation staging (2002 system) and the influence of this information on freedom from biochemical failure (bNED). Prostate biopsy laterality status (unilateral versus bilateral positive) is part of clinical staging using American Joint Commission on Cancer criteria, but is rarely used. Methods. From April 1, 1989 to September 30, 1999, 1038 patients with palpable T1-T3Nx-0M0 prostate cancer were treated with three-dimensional conformal radiotherapy alone. Kaplan-Meier bNED curves were compared using the log-rank test. The Cox proportional hazards regression model of bNED was used for multivariate analysis. Results. The median follow-up was 46 months. The proportion of patients with bilateral positive biopsies by palpation category T1c was 24%, by T2a was 17%, by T2b was 26%, by T2c was 65%, and by T3 was 53%. No statistically significant difference was noted in bNED on the basis of biopsy laterality status for the palpation T stages T1c, T2a, T2b, or T3. A statistically significant difference in the 5-year bNED in the T2c stage was found; those with unilateral positive biopsies fared worse (46% versus 74%, respectively, P = 0.04). Conclusions. Inclusion of positive biopsy laterality status into clinical staging causes stage migration without reflecting a change in outcome and should not be used.