Nadir prostate-specific antigen best predicts the progression to androgen-independent prostate cancer.

The objective of our study was to analyze the value of prostate-specific antigen (PSA) levels before and after androgen suppression to predict the time to androgen-independent progression (AIP) in patients with advanced and metastatic prostate cancer. A series of 283 prostate cancer patients under androgen suppression as a single treatment was studied. The disease was locally advanced in 98 patients and metastatic in the remainder 185. AIP was defined after 2 consecutive increases of serum PSA after the nadir value. The mean follow-up before AIP was 29.2 months (3-198). AIP was detected in 205 patients (72.4%). In 152 patients (74.1%), the event was detected within 24 months, while in 53 patients (25.9%), it was observed beyond 24 months. The multivariate analysis showed that the nadir PSA and the time to reach the nadir PSA were the most significant predictors of the time to AIP. The odds ratio of having a biochemical response greater than 24 months was 20 times higher in patients that achieved an undetectable PSA level of 0.2 ng/mL or less. Moreover in those patients whose nadir PSA reached beyond 12 months after androgen suppression the odds ratio was 18 times higher. These results show that the ability to achieve an undetectable nadir PSA and the time to reach it are the most significant predictors of the time to AIP in patients with locally advanced and metastatic prostate cancer under androgen suppression as a single therapy.