THE NATURAL HISTORY OF ANDROGEN INDEPENDENT PROSTATE CANCER

Abstract

We describe the natural history of androgen independent prostate cancer (AIPC) in the modern prostate specific antigen (PSA) era. Data from 160 patients diagnosed with AIPC between 1989 and 2002 were reviewed. No patient had received cytotoxic chemotherapy. Univariate and multivariate proportional hazards models were constructed to identify significant risk factors for cancer specific survival. Recursive partitioning analysis stratified patients into prognostic risk groupings. The types and frequencies of cancer specific complications per risk grouping were compared. The final prognostic risk model included nadir PSA on androgen deprivation therapy (p = 0.023), time to PSA recurrence (p = 0.006) and prostate specific antigen doubling time (p <0.01). Three highly independent risk groupings were identified. The observed median cancer specific survivals were 14.0 months (95% CI, 8.3-19.8), 38.4 months (95% CI, 26.9-49.9) and 89.1 months (95% CI, 69.0-109.2) for low, intermediate and high risk groupings, respectively (p <0.001). Patients in the low risk grouping experienced significantly fewer cancer specific complications (p = 0.003). This prognostic model stratified patients into 3 highly significant and independent risk groupings. A detailed PSA history alone is sufficient to risk stratify patients with AIPC.