Optimizing patient selection for dose escalation techniques using the prostate-specific antigen level, biopsy Gleason score, and clinical T-stage

Purpose: Ideal candidates for 3D dose escalation conformal radiation or external beam + implant therapy are identified on the basis of the prostate- specific antigen (PSA) level, biopsy Gleason score, and the 1992 American Joint Commission Cancer (AJCC) clinical T-stage. Methods and Materials: The pathologic findings of 1742 men with clinical stage T1c,2 prostate cancer managed with a radical prostatectomy (RP) between 1990 and 1998 were subjected to a logistic regression multivariable analysis. The endpoints examined included pathologic organ-confined (OC), specimen-confined (SC), and margin (M) or seminal vesicle (SV) positive disease. SC disease was defined as extracapsular extension (ECE) with a negative surgical margin. The clinical factors tested included PSA level, biopsy Gleason score, and the 1992 AJCC clinical T-stage. PSA failure-free (bNED) survival was calculated according to the method of Kaplan and Meier. Results: Significant negative predictors of pathologic OC-disease or positive predictors of M⁺ or SV⁺ disease included a PSA > 10 ng/ml (p < 0.0001), biopsy Gleason score ≥7 (p ≤ 0.0004), and ≥ T2b disease (p ≤ 0.03). Only biopsy Gleason score 7 (p = 0.0006) and PSA 10-15 ng/ml (p = 0.04) were significant predictors of SC disease. The estimates of 5-year bNED survival were 80%, 62%, and 35% (p < 0.0001) for patients having a low, intermediate, or high likelihood of having M⁺ or SV⁺ disease respectively. Conclusions: Patients most likely to derive a survival benefit from the improved local control possible using dose escalation techniques were those who had both a low risk of having occult micrometastatic disease (< 25% M⁺ or SV⁺) and a reasonable likelihood of remaining disease-free after RP (>50% 5-year bNED). These patients included those having T1c, 2a, PSA > 10-15 ng/ml, and biopsy Gleason ≤6 or T1c, 2a, 2b, PSA ≤ 10 ng/ml, and biopsy Gleason ≤ 7 prostate cancer.