Mortality results from the Göteborg randomised population-based prostate-cancer screening trial

Abstract

Summary Background Prostate cancer is one of the leading causes of death from malignant disease among men in the Western world. One strategy to decrease the risk of dying from this disease is screening with Prostate-Specific Antigen (PSA); however, the extent of benefit and harm with such screening is under continuous debate. Methods In December 1994, 20 000 men born 1930 to 1944, randomly sampled from the Population Register, were computer randomised in a 1:1 ratio to a screening group invited for biennial PSA testing or to a control group not invited. In each arm, 48 men were excluded from analysis due to either death or emigration before randomization date or prevalent prostate cancer. The primary endpoint was prostate cancer specific mortality analyzed according to the intention-to-screen principle. Men in the screening group were invited up to the upper age limit (median 69, range 67–71 years) and only men with elevated PSA were offered additional tests such as digital rectal examination and prostate biopsies. The study is still ongoing inviting men who have not yet reached the upper age limit. This is the first planned report on cumulative prostate cancer incidence and mortality calculated up to Dec 31 2008. This study is registered [as an International Standard Randomised Controlled Trial], number [ISRCTN49127736]. Findings Among men randomised to screening 7578/9952 (76%) attended at least once (attendees). During a median follow-up of 14 years, 1138 men in the screening group and 718 in the control group were diagnosed with prostate cancer resulting in a cumulative incidence of prostate cancer of 12.7% in the screening arm and 8.2% in the control arm (hazard ratio 1.64; 95% confidence interval [CI] 1.50–1.80; p<0.0001). The absolute cumulative risk reduction of death from prostate cancer at 14 years was 0.40% (95% CI 0.17–0.64%), from 0.90% in the control group to 0.50% in the screening group. The incidence rate ratio for death from prostate cancer was 0.56 (95% CI 0.39–0.82; p=0.002) in the screening compared to the control group. The incidence rate ratio of attendees compared to the control group was 0.44 (95% CI 0.28–0.68; p=0.0002). Overall, 293 men needed to be invited for screening and 12 to be diagnosed to prevent one prostate cancer death. Interpretation The benefit of prostate cancer screening compares favourably to other cancer screening programs and in this study prostate cancer mortality was reduced almost by half over 14 years. However, the risk of over diagnosis is substantial and the number needed to treat is at least as high as in breast cancer screening. Funding The Swedish Cancer Society, the Swedish Research Council and the National Cancer Institute.