The Relationship Of Ultrasensitive Measurements Of Prostate-specific Antigen Levels To Prostate Cancer Recurrence After Radical Prostatectomy

A rising PSA following radical prostatectomy (RP) for prostate cancer (CaP) suggests disease recurrence. Ultrasensitive PSA (USPSA) tests can detect PSA at values as low as 0.001ng/ml. Dr. Taylor and colleagues publish a report in the September 2006 issue of the BJU International that evaluates USPSA values in the context of clinical outcomes.

A cohort of 225 patients who underwent RP between 1997 and 2001 had up to 65 months of follow-up. PSA was measured by the Elecsys (Roche) USPSA assay, with a sensitivity of 0.002ng/ml. Clinical and demographic data was collected and correlated.

Patients were separated into those with disease recurrence and those without. USPSA levels for each group were put into pre-set periods that were established to approximate follow-up times of 6, 12, 18, 24, 36 and 60 months.

Follow-up was similar for the 2 groups, with a median of 31 months. In patients with disease recurrence, the pretreatment PSA levels and age were slightly higher. A USPSA level of >0.002ng/ml was found in 21 men; 11 then received salvage radiotherapy and/or androgen deprivation therapy. Ten patients went on observation and all had USPSA levels that continued to rise. A significant difference was found in the recurrence and no recurrence groups for every time point except 60 months. USPSA levels remained constant in those without recurrence. Of those with no recurrence, 89 patients (44%) had an undetectable PSA level outside the range of the USPSA assay during the follow-up; only 3 of 21 (14%) with a recurrence attained this level (P=0.009).

Fluctuations in the USPSA levels precluded calculating useful PSA kinetics. Although there were statistically significant differences in USPSA levels between groups, the clinical translation was meaningless due to the significant overlap of the two groups. This possibly reflects 'assay noise'. However, an undetectable USPSA level was associated with a favorable outcome. Presently, USPSA assays do not have adequate data to substantiate their use in initiating salvage therapy in CaP patients with detectable levels after RP.

By Christopher P. Evans, M.D.

BJU International
?Volume 98 Page 540-543  - September 2006

Link Here.
JOHN A. TAYLOR III, STACEY G. KOFF, DEBORAH A. DAUSER and DAVID G. McLEOD

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