Ultrasensitive assay of prostate-specific antigen used for early detection of prostate cancer relapse and estimation of tumor-doubling time after radical prostatectomy

Abstract

We used an ultrasensitive prostate-specific antigen (PSA) assay with a detection limit of 0.02 microgram/L for long-term monitoring of PSA changes in 5 patients who were cured by radical prostatectomy and in 10 patients who had failed prostatectomies; 5 patients who underwent cystoprostatectomy were also evaluated with one sample after surgery. Relapse-free periods, determined on the basis of criteria designed specifically for the ultrasensitive assay or proposed for other currently available PSA assays, were calculated for the patients with failed prostatectomies. Tumor-doubling times were also calculated, postsurgery, according to a model that assumes exponential tumor growth over time. We found that prostate cancer relapse, on average, could be diagnosed 420 or 883 days earlier with the ultrasensitive assay than with assays having detection limits of 0.1 or 0.3 microgram/L, respectively. Tumor-doubling times, calculated after radical prostatectomy, ranged from 67 to 568 days among the 10 patients. We also present evidence that even more-sensitive PSA assays might be able to further reduce the relapse-free periods in approximately 50% of the prostate cancer patients who ultimately relapse.

Prostate specific antigen nadir determined using ultra‐sensitive prostate specific antigen as a predictor of biochemical progression after radical prostatectomy in Japanese males

“…By 3 and 6 months after radical prostatectomy, the PSA values of 62.6% and 92.1% of the patients had reached nadir, respectively. These findings differed from those of Shen et al 10,23 If follow-up intervals were short enough, the time between radical prostatectomy and PSA nadir may be found to be brief, as our findings indicate. We believe that earlier salvage radiotherapy increases curability, as Terai et al showed.…”

“…Several reports showed that biochemical progression can be diagnosed 1-2 years earlier with ultra-sensitive PSA than with non-ultra-sensitive PSA. 8,10,11 The most important conclusion to be reached from those findings is that very small PSA changes can be detected that could not be detected previously.…”

“…Serum PSA levels were undetectable (less than 0.008 ng/mL) in 86.2% of radical cystoprostatectomy patients and 61.9% of radical prostatectomy patients, 8 and 70% of patients with non-aggressive prostate cancer had PSA values of less than 0.02 ng/mL 9 Biochemical recurrence after radical prostatectomy could be diagnosed 1-2 years earlier with an ultra-sensitive assay than with conventional assays. 8,10,11 Recently, Shen et al reported that PSA nadir can be a good predictor of biochemical failure after radical prostatectomy. 12 In this study, we examined whether PSA nadir determined using an ultra-sensitive PSA assay, together with other clinicopathological factors, is a potentially good predictor of biochemical progression after radical prostatectomy in a Japanese cohort.…”

Diagnosis of local recurrence after radical prostatectomy

“…Ultrasensitive PSA assays that detect serum PSA levels of < 0.01 ng/mL may reveal a relapse of prostate cancer even 1 or 2 years earlier than the conventional assay, but the clinical utility is limited by higher rates of false‐positive results [6].…”

The relationship of ultrasensitive measurements of prostate‐specific antigen levels to prostate cancer recurrence after radical prostatectomy

“…Ultrasensitive (US) PSA assays were first introduced in 1993 [2,3]; technical modifications have allowed for increasing assay sensitivity to <0.1 ng/mL, and assays capable of detecting levels as low as 0.001 ng/mL are now widely available [4]. Researchers suggested that these newer, more sensitive PSA assays can be used to detect cancer recurrence earlier [3,5]. The initial tendency was to use these tests for those patients deemed to be at greater risk of recurrence.…”