Purpose: To determine whether pretreatment risk groups shown to predict time to prostate cancer-specific mortality (PCSM) after treatment at a single institution retained that ability in a multi-institutional setting.
Patients and methods: From 1988 to 2002, 7,316 patients treated in the United States at 44 institutions with either surgery (n = 4,946) or radiation (n = 2,370) for clinical stage T1c-2, N0 or NX, M0 prostate cancer made up the study cohort. A Cox regression analysis was performed to determine the ability of pretreatment risk groups to predict time to PCSM after treatment. The relative risk (RR) of PCSM and 95% confidence intervals (CIs) were calculated for the intermediate- and high-risk groups relative to the low-risk group.
Results: Estimates of non-PCSM 8 years after prostate-specific antigen (PSA) failure were 4% v 15% (surgery versus radiation; Plog rank =.002) compared with 13% v 18% (surgery versus radiation; Plog rank =.35) for patients whose age at the time of PSA failure was less than 70 as compared with >or= 70 years, respectively. The RR of PCSM after treatment for surgery-managed patients with high- or intermediate-risk disease was 14.2 (95% CI, 5.0 to 23.4; PCox <.0001) and 4.9 (95% CI, 1.7 to 8.1; PCox =.0037), respectively. These values were 14.3 (95% CI, 5.2 to 24.0; PCox <.0001) and 5.6 (95% CI, 2.0 to 9.3; PCox =.0012) for radiation-managed patients.
Conclusion: This study provided evidence to support the prediction of time to PCSM after surgery or radiation on the basis of pretreatment risk groups for patients with clinically localized prostate cancer managed during the PSA era.