Impact of the percentage of positive prostate cores on prostate cancer-specific mortality for patients with low or favorable intermediate-risk disease.

PURPOSE: We investigated whether pretreatment factors predicted time to prostate cancer-specific mortality (PCSM) after conventional-dose and conformal radiation therapy (CRT). PATIENTS AND METHODS: Between 1988 and 2002, 421 patients with low (prostate-specific antigen [PSA] level < or = 10 ng/mL and biopsy Gleason score < or = 6) or favorable intermediate-risk (PSA > 10 to 15 ng/mL or biopsy Gleason score 3 + 4, but not both factors) disease underwent CRT (median dose, 70.4 Gy). Cox regression multivariable analysis was performed to determine whether the PSA level, Gleason score, T category, or the percentage of positive cores (% PC) predicted time to PCSM after CRT. After a median follow-up of 4.5 years, 117 (28%) patients have died.
RESULTS: The % PC was the only significant predictor (Cox P < or =.03). The relative risk of PCSM after CRT for patients with > or = 50% as compared with less than 50% PC was 10.4 (95% CI, 1.2 to 87; Cox P =.03), 6.1 (95% CI, 1.3 to 28.6; Cox P =.02), and 12.5 (95% CI, 1.5 to 107; Cox P =.02) in men with a PSA < or = 10 and Gleason score < or = 6, PSA < or = 10 and Gleason score < or = 7, and PSA < or = 15 and Gleason score < or = 6, respectively. By 5 years after CRT, 5% to 9% compared with less than 1% (log-rank P < or =.01) of these patients experienced PCSM if they had > or = 50% compared with less than 50% PC, respectively.
CONCLUSION: CRT dose-escalation techniques, the addition of hormonal therapy, or both should be considered in the management of patients with low or favorable intermediate-risk disease and > or = 50% PC.