The impact of reducing the frequency of prostate specific antigen (PSA) testing among men on active surveillance for prostate cancer.
5092 Background: Active surveillance is a management strategy for men with low risk prostate cancer. Most surveillance regimens include routine PSA assessments, typically performed q 3 mos, although recent studies have questioned the utility of short-term PSA kinetics. Moreover, frequent PSA assessments may be associated with repeated intervals of anxiety around the time of testing, decreasing overall quality of life and potentially leading to avoidable interventions. We hypothesized that PSA assessment q 6 mos rather than q 3 mos would yield similar PSA kinetics calculations. Methods: We analyzed data from the Prostate Active Surveillance Study (PASS), a prospective, multicenter cohort accruing data and biospecimens from men on surveillance at 9 sites across North America. In PASS, PSAs are measured q 3 mos, with high completeness of data. We included data from men who had at least 5 PSA assessments after diagnosis, separated by ≥6 months (most had 10 PSAs separated by 3 months). PSA doubling time (PSADT) was calculated as ln(2) divided by the slope of a regression line drawn through the 5 PSAs. PSADT3 and PSADT6 were defined as the PSADT calculated from q 3 mos and q 6 mos data, respectively; for PSADT6, PSAs between each 6-month measurement were ignored. In each case, PSADT of 0-3 years defined progression, and PSADT > 3 years or declining PSA defined non-progression. Results: 161 men had sufficient PSA followup for analysis. 133 had no progression by either PSADT3 or PSADT6, and 16 progressed by both PSADT calculations. 4 and 8 men, respectively, progressed only by the PSADT3 or PSADT6 calculation but not by the other calculation. The κ score for agreement of progression ascertainment between PSADT3 and PSADT6 was 0.68, and McNemar’s test indicated no statistically significant difference between the two assessments (p=0.39). Conclusions: Calculating PSADT using 6-month rather than 3-month PSA assessments does not significantly change ascertainment of PSA progression in men on surveillance. Our finding suggests that surveillance protocols may reduce the frequency of PSA testing, potentially reducing unnecessary biopsy procedures and patient anxiety due to more frequent PSA measurements.