Prostate-specific antigen level at initiation of hormonal therapy after prostate-specific antigen failure following prostatectomy or radiotherapy and therapeutic response.

OBJECTIVES

To determine the pretreatment factors associated with an undetectable prostate-specific antigen (PSA) nadir after 8 months of androgen suppression therapy (AST).

METHODS

The study cohort comprised 137 men with an increasing PSA level after surgery or radiotherapy performed for localized prostate cancer who had undergone AST. Cox regression multivariate analyses were used to identify the factors associated with a PSA nadir of 0.2 ng/mL or less 8 months after AST initiation.

RESULTS

The PSA level at the initiation of AST was associated with a PSA nadir of 0.2 ng/mL or less after 8 months of AST, as both a continuous variable (adjusted odds ratio [OR] 0.44, P = 0.0001) and a categorical variable, with PSA greater than 10 ng/mL (OR 0.16, P = 0.007). The percentage of patients with a PSA nadir of 0.2 ng/mL or less was 86%, 72%, 75%, 67%, and 25% for men with a PSA level at the initiation of AST of 4 ng/mL or less, greater than 4 to 10 ng/mL, greater than 10 to 20 ng/mL, greater than 20 to 50 ng/mL, and greater than 50 ng/mL, respectively.

CONCLUSIONS

An elevated PSA level before the initiation of AST was significantly associated with a decreased chance of a PSA nadir of 0.2 ng/mL or less after 8 months of AST. Given the association between the PSA nadir after AST and prostate-cancer specific mortality, men with increasing PSA levels could be considered for Phase II and III clinical trials evaluating the effect of adding novel systemic therapies to AST on the interval to prostate-cancer specific mortality.