Recurrent prostate cancer despite undetectable prostate specific antigen.

Serum prostate specific antigen (PSA) is a sensitive tumor marker following definitive therapy for adenocarcinoma of the prostate. Detectable levels of PSA after radical prostatectomy indicate residual and/or recurrent cancer. Therefore, we were surprised to document recurrent cancer following radical retropubic prostatectomy in a man who had undetectable serum PSA levels. This observation suggests that careful clinical monitoring remains essential after definitive therapy, since rare patients may have recurrent and/or residual carcinoma despite undetectable levels of PSA.