Would prostate cancer detected by screening with prostate-specific antigendevelop into clinical cancer if left undiagnosed? A comparison of two population-based studies in Sweden

Objective To assess the risk. of over-diagnosing and over-treating prostate cancer if population-based screening with serum prostate-specific antigen (PSA) is instituted. Patients and methods From a serum bank stored in 1980, PSA was analysed in 658 men with no previously known prostate cancer from a well-defined cohort from Goteborg, Sweden (men born in 1913); the incidence of clinical prosta te cancer was registered until 1995. From the same area, and with the same selection criteria, another cohort of 710 men born in 1930-31, who in 1995 accepted an invitation for PSA screening, was also analysed. Results Of men born in 1913, 18 (2.7%) had died from prostate cancer and th e cumulative probability of being diagnosed with clinical prostate cancer w as 11.1% (5.0% in those with a PSA level of <3 ng/mL vs 32.9% in those with a PSA level of >3 ng/mL, P<0.01). The mean lead-time from increased PSA (> 3 ng/mL) to clinical diagnosis was 7 years. The prostate cancer detection r ate in men born in 1930-31 was 4.4% (22% among those with increased PSA lev els) and 30 of 31 detected cancers were clinically localized. Conclusions Screening and sextant biopsies resulted in a lower detection ra te (22%) than the cumulative risk of having clinical prostate cancer (33%) in men with increased PSA levels, indicating that under-diagnosis rather th an over-diagnosis is the case at least with 'one-time' screening. Even if t he stage distribution in screening-detected cancers seems promising (and th us may result in reduced mortality) it is notable that screening 67-year-ol d men will result in treatment a mean of 7 years before clinical symptoms o ccur and only one in four men anticipated to develop prostate cancer will d ie from the disease within 15 years. Large randomized screening trials seem mandatory to further explore the benefits and hazards of PSA screening.