Nadir prostate-specific antigen as a predictor of progression to androgen-independent prostate cancer

Objectives. To determine the value of the before and after treatment level of prostate-specific antigen (PSA) to predict the time to androgen-independent progression (AIP) in patients with advanced prostate cancer who received androgen-deprivation therapy (ADT) at the time of recurrence or progression. Methods. The records of 153 patients with advanced or metastatic prostate cancer who were treated with ADT were retrospectively reviewed. Fifty-six percent of the patients were initially treated with ADT. In the remainder, ADT was started at progression and/or failure. AIP was defined as two consecutive elevations of serum PSA above the nadir value by any threshold. Kaplan-Meier and multiple logistic regression analyses were used to determine the potential predictors of AIP. Results. The median duration of the PSA response was 24 months. The most important predictors of the time to AIP were the initial Gleason grade and the nadir PSA level after the initiation of ADT. The odds ratio of having a response greater than 24 months was 15-times higher in patients achieving an undetectable serum PSA level versus those who did not. For each point increase in the Gleason sum, patients had a five times higher chance of progressing to AIP in 24 months or less. Conclusions. The ability to achieve an undetectable nadir PSA level and the initial Gleason grade are significant predictors of the time to AIP in men treated with ADT for metastatic and advanced prostate cancer.