The prostate-specific antigen (PSA) is the main biomarker for diagnosis and treatment response monitoring in prostate cancer (PCa). In the first part of this thesis, we investigated the prognostic value of ultrasensitive PSAs (u-PSAs) in evaluating the risk of biochemical recurrence (BCR) and further progression after radical prostatectomy (RP). BCR after RP is defined by two consecutive PSA values greater or equal to 0.2 ng/ml. We found that u-PSA values above the threshold of 0.02-0.03 ng/ml predict progression to the BCR threshold (> 0.2 ng/ml). Furthermore, we demonstrated that the longitudinal modeling of u-PSA doubling time (uDT) could predict BCR after RP with very low PSA values. This can be beneficial in helping practitioners to avoid unnecessary adjuvant treatments or to start salvage treatments earlier for selected patients. 

In the second part of this thesis, PCa survival and mortality was investigated in the pre- and post-PSA eras. One of the cohort studies evaluated the impact of socioeconomic status (SES) on the survival of PCa patients in the pre- and post-PSA eras. Our study showed that men with localized PCa are otherwise healthier than the general male population, and the increased difference between relative and cancer-specific survival reflects the most likely selection of men for opportunistic PSA-testing. Men in higher SES groups had significantly lower risks of dying from PCa than those in the lower SES groups, which was probably due to more intensive diagnostic/treatment strategies and the increased intensity of health conscious men seeking medical services such as PSA testing.