Cumulative risk of developing prostate cancer in men with low (2.0ng/mL) prostate-specific antigen levels: A population-based screening cohort study in Japan

Objectives To investigate the natural history of men with low levels of baseline prostate-specific antigen in terms of risk of increased prostate-specific antigen, developing prostate cancer and also the likelihood of detecting clinically insignificant cancer in population-based screening. Methods A total of 10653 men aged between 55 and 68 years with baseline prostate-specific antigen levels of 2.0ng/mL or lower screened annually were enrolled. The cumulative risks of increased prostate-specific antigen and developing cancer were investigated. The relationships of baseline prostate-specific antigen with clinicopathological features of screening-detected cancer were also investigated. Results A total of 1405 men (13.2%) showed serum prostate-specific antigen above 2.0ng/mL and 68 (0.6%) were diagnosed with prostate cancer during the observation period. Cumulative probabilities of increased prostate-specific antigen above 2.0ng/mL over 10 years were 7.7%, 18.3%, 57.3%, and 88.7% in men with baseline prostate-specific antigen levels of 0.0-0.5, 0.6-1.0, 1.1-1.5, and 1.6-2.0ng/mL, respectively. The cumulative probabilities of developing prostate cancer at 4 years in men with baseline prostate-specific antigen of 0.0-1.0 and 1.1-2.0ng/mL were 0.05% and 1.10%, respectively. Patients with unfavorable clinicopathological features were diagnosed at 3 years, and at 1 year after the initial screening visit in men with baseline prostate-specific antigen levels of 0.0-1.0 and 1.1-2.0ng/mL, respectively. Conclusions The cumulative probabilities of increased prostate-specific antigen and developing prostate cancer significantly increase with higher baseline prostate-specific antigen ranges. Our database could contribute to the establishment of a natural history-adjusted screening system in the future.