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

Abstract

Background: Prostate cancer is one of the leading causes of death from malignant disease among men in the developed world. One strategy to decrease the risk of death 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 between 1930 and 1944, randomly sampled from the population register, were randomised by computer in a 1:1 ratio to either a screening group invited for PSA testing every 2 years (n=10,000) or to a control group not invited (n=10,000). Men in the screening group were invited up to the upper age limit (median 69, range 67-71 years) and only men with raised PSA concentrations were offered additional tests such as digital rectal examination and prostate biopsies. The primary endpoint was prostate-cancer specific mortality, analysed according to the intention-to-screen principle. The study is ongoing, with men who have not reached the upper age limit invited for PSA testing. 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 ISRCTN54449243.

Findings: In each group, 48 men were excluded from the analysis because of death or emigration before the randomisation date, or prevalent prostate cancer. In men randomised to screening, 7578 (76%) of 9952 attended at least once. 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 prostate-cancer incidence of 12.7% in the screening group and 8.2% in the control group (hazard ratio 1.64; 95% 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 rate ratio for death from prostate cancer was 0.56 (95% CI 0.39-0.82; p=0.002) in the screening compared with the control group. The rate ratio of death from prostate cancer for attendees compared with the control group was 0.44 (95% CI 0.28-0.68; p=0.0002). Overall, 293 (95% CI 177-799) men needed to be invited for screening and 12 to be diagnosed to prevent one prostate cancer death.

Interpretation: This study shows that 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 programmes. The benefit of prostate-cancer screening compares favourably to other cancer screening programs.

Funding: The Swedish Cancer Society, the Swedish Research Council, and the National Cancer Institute.

Figure 1

CONSORT diagram of the study

Figure 2

Cumulative incidence of prostate cancer in the screening group and in the control group

Figure 3

Cumulative risk of death from prostate cancer using Nelson-Aalen cumulative hazard estimates