Limitations of prostate specific antigen doubling time following biochemical recurrence after radical prostatectomy: results from the SEARCH database.

PURPOSE: Prostate specific antigen doubling time following biochemical recurrence after radical prostatectomy is a powerful predictor of prostate cancer specific and overall death. To calculate prostate specific antigen doubling time requires multiple prostate specific antigen determinations that are unaltered by secondary therapy and separated by sufficient time. Physicians and patients may be unwilling to wait before starting secondary therapy, especially for high risk recurrences. Hence, those with calculable prostate specific antigen doubling time may represent a select lower risk group relative to all men with biochemical recurrence.
MATERIALS AND METHODS: We compared clinical and pathological features between patients with and without calculable prostate specific antigen doubling time. We assessed time trends in the proportion with calculable prostate specific antigen doubling time in 535 patients with biochemical recurrence after radical prostatectomy at 5 Veterans Affairs medical centers comprising the SEARCH (Shared Equal Access Regional Cancer Hospital) database between 1988 and 2003.
RESULTS: Prostate specific antigen doubling time was not calculable in 187 patients (35%) due to secondary therapy in 155 (83%). With time the proportion of patients with calculable prostate specific antigen doubling time decreased significantly (p <0.001). Adverse pathological features, more rapid time to recurrence, higher body mass index and differing surgical centers were associated with not having a calculable prostate specific antigen doubling time. Of all men with recurrence in the most recent year of analysis the adjusted probability of having a calculable prostate specific antigen doubling time was only 43%, that is 61% in patients with favorable pathological results but only 30% in those with seminal vesicle invasion.
CONCLUSIONS: Those with calculable prostate specific antigen doubling time represented a select, lower risk cohort and the proportion of patients with calculable prostate specific antigen doubling time decreased with time. This highlights the need for alternative markers in men with recurrent prostate cancer because one of our best current markers, prostate specific antigen doubling time, is only available in a limited number of patients.