RESUMO
BACKGROUND: Annual changes in prostate specific antigen (PSA) levels detected by the Imari prostate cancer screening program were evaluated to establish a more efficient and cost-saving screening system, especially for men with low PSA levels. METHODS: Prostate specific antigen-based annual mass screenings for prostate cancer were conducted for men aged 60-69 in the Imari district, Saga, Japan. Between 1992 and 2000, 1822 men had their PSA levels tested. A total of 4661 PSA tests were conducted. Changes in PSA levels over the following 1 to 5 years were analyzed in men with PSA levels of 3 ng/mL or less, a range in which the detection rate of prostate cancer would seem to be negligibly low. RESULTS: The overall detection rate of prostate cancer between 1992 and 2000 was 0.73%. The detection rate in men with a PSA level between 3.1 and 3.9 ng/mL, and between 4 and 9.9 ng/mL was 1.6% and 8.3%, respectively. Of 4661 determinations of PSA, 2553 (54.8%) were found to be < or = 1 ng/mL, 1273 (27.3%) were between 1.1 and 2 ng/mL, and 401 (8.6%) were between 2.1 and 3 ng/mL. Four hundred and thirty-four men (9.3%) had PSA levels > or = 3.1 ng/mL, with possible indications for prostate biopsy. Of the men tested, 1.4% with an initial PSA level of < or = 2 ng/mL and 22.3% with an initial level between 2.1 and 3 ng/mL had a PSA level of > or = 3.1 ng/mL after 1 year. Almost the same rate of PSA increase was observed between the two PSA tests conducted at 2 to 5-year intervals. Of the men tested, 2.2% with an initial PSA level of < or = 2 ng/mL, and 21.9% with an initial level between 2.1 and 3 ng/mL, had a level of > or = 3.1 ng/mL after 5 years. CONCLUSION: Levels of PSA in men with an initial level below 2 ng/mL remained stable for up to 5 years. Levels of PSA in 97.8- 98.8% of men remained below 3 ng/mL after 1 to 5 years. In contrast, 18-35.3% of men with an initial PSA level between 2.1 and 3 ng/mL showed PSA progression to 3.1 ng/mL or more within 5 years. Our present data suggest that annual PSA testing is not necessary for men with a PSA level below 2 ng/mL. Prostate specific antigen testing could therefore be conducted at longer intervals in such individuals.