Prognostic model of event-free survival for patients with androgen-independent prostate carcinoma.

Background: The current study was conducted to develop a prognostic model of event-free survival (EFS) in men with androgen-independent prostate carcinoma (AIPC).

Methods: Data from 160 patients diagnosed with AIPC between 1989-2002 were reviewed. No patient had received cytotoxic chemotherapy. A univariate Cox proportional hazards model identified significant predictors of EFS. Recursive partitioning analysis divided these significant variables into prognostic risk groups. The final prognostic model was tested with a Cox proportional hazards model.

Results: The final prognostic risk model included the presence of metastatic disease at the time of androgen-independent disease progression (P = 0.040), time to prostate-specific antigen (PSA) recurrence (P = 0.043), and PSA doubling time (P < 0.01). Three highly independent risk groups were identified. The observed median EFSs were 6.1 months (95% confidence interval [95= CI], 3.4-8.8 months), 33.6 months (95= CI, 25.3-41.9 months), and 96.1 months (95= CI, 57.9-134.3 months) for the low-risk, intermediate-risk, and high-risk groups, respectively. Each risk group was found to be independently predictive of EFS (P < 0.01). Patients who died of prostate carcinoma experienced significantly more clinical events than those who died of other causes (P < 0.01).

Conclusions: The prognostic model in the current study stratified patients into three highly significant and independent risk groups for EFS. A detailed PSA history and knowledge of metastatic disease are sufficient to risk-stratify patients with AIPC. One very unique aspect of this model was that it was developed from a patient cohort that never received chemotherapy.