Delays in cancer detection using 2 and 4-year screening intervals for prostate cancer screening with initial prostate specific antigen less than 2 ng/ml

Purpose: The American Urological Association and American Cancer Society advocate annual screening with serum prostate specific antigen (PSA) and digital rectal examination starting at age 50 years in the general population and earlier in men at high risk. Some groups have suggested that screening at 2 or 4-year intervals may be sufficient in men with initial PSA 2 ng/ml or less. We reviewed the records of men enrolled in a PSA and digital rectal examination based prostate cancer screening study to determine the extent to which the diagnosis of cancer would have been delayed using a 2 or 4-year screening interval. Materials and Methods: We evaluated 18,140 volunteers in a prostate cancer screening study in whom PSA was less than 2 ng/ml at initial screening and who were screened at 6-month to 1-year intervals for up to 8 years. We evaluated the cancers detected in these intervals to determine the possible delay in cancer diagnosis that would occur using prolonged screening intervals. We report the overall cancer detection rate, clinical and pathological tumor stage, and Gleason grade of the cancers detected. Results: Excluding 70 men in whom prostate cancer was detected at initial evaluation 2.0% had prostate cancer detected during the next 8 years (mean 21.6 cancers per 6 months, median 20, range 12 to 33). Using a hypothetical 2-year screening interval cancer detection 62% would have been delayed by 4 to 20 months. Using a hypothetical 4-year screening interval cancer detection would have been delayed in 77% of men by 4 to 44 months. Of the tumors detected 100% were clinically localized, 77% were pathologically organ confined and 29% had a Gleason score of 7 or greater. Conclusions: The 2 or 4-year PSA screening interval in men with initial serum PSA less than 2 ng/ml would result in substantial delays in prostate cancer detection. To our knowledge the extent to which these delays would affect treatment outcomes is undetermined.