Pathologic features of prostate cancer found at population-based screeningwith a four-year interval

Background: The currently recommended frequency for prostate-specific antig en (PSA) screening tests for prostate cancer is I year, but the optimal scr eening interval is not known. Our goal was to determine if a longer interva l would compromise the detection of curable prostate cancer. Methods: A coh ort of 4491 men aged 55-75 years, all participants in the Rotterdam section of the European Randomized Study of (population-based) Screening for Prost ate Cancer, were invited to participate in an initial PSA screening. Men wh o received that screening were invited for a second screen 4 years later. P athology findings from needle biopsy cores were compared for men in both ro unds. Statistical tests were two-sided. Results: A total of 4133 men were s creened in the first round (the prevalence screen), and 2385 were screened in the second round. The median amount of cancer in needle biopsy sets was 7.0 mm (95 % confidence interval [CII = 5.4 mm to 8.6 mm) in the first roun d and 4.1 min (95% CI = 2.6 mm to 5.6 mm) in the second round (P =.001). Th irty-six percent of the adenocarcinomas detected in the first round but onl y 16% of those detected in the second round had a Gleason score of 7 or hig her (mean difference = 20% [95% C1 = 10% to 30%]; P < .001). Whereas 25% of the adenocarcinomas detected in the first round had adverse prognostic fea tures, only 6 % of those detected in the second round did (mean difference = 19% [95% CI = 11% to 26%]; P < .001). Baseline PSA values were predictive for the amount of tumor in biopsies in men with cancer in the first round but not for that in the second round. Conclusion: Most large prostate cance rs with high serum PSA levels were effectively detected in a prevalence scr een. In this population, a screening interval of 4 years appears to be shor t enough to constrain the development of large tumors, although it is incon clusive whether this will result in a survival benefit.