Am Fam Physician. 2007;75(3):336-337
Screening for Prostate Cancer
Does screening for prostate cancer reduce all-cause or prostate-cancer–specific mortality or impact quality of life?
There is insufficient evidence to determine whether screening for prostate cancer reduces mortality or impacts quality of life.
This Cochrane review identified two randomized controlled trials (RCTs) comparing mass screening for prostate cancer to no screening: the Quebec trial and the Norrkoping trial. Both studies reported data on prostate cancer incidence, disease-specific mortality, stage at diagnosis, and treatment follow-up. Neither study reported data on quality of life, all-cause mortality, costs, or adverse effects of screening (e.g., false-negative or false-positive results, adverse effects of biopsy, treatment complications). These studies had serious methodologic flaws resulting in a high risk of bias.
The Quebec trial recruited men 45 to 80 years of age from electoral registrations in Quebec City, Canada. A total of 31,133 men were randomly selected to be offered screening, and 15,353 were not invited to screening. Men with prostate cancer and those previously screened and referred to the study's clinic were excluded. Screening was performed annually by a digital rectal examination (DRE) and prostate-specific antigen (PSA) test; by DRE, PSA, and transrectal ultrasound-guided biopsy; or by PSA alone.
The reported relative risk (RR) of death from prostate cancer in men who were screened was 0.39 (95% confidence interval, 0.19 to 0.65). However, only 23 percent of those invited for screening were screened, and 7.3 percent in the nonscreening control group were screened. To address this high rate of crossover from the invited group to the uninvited group, the Cochrane reviewers performed intention-to-treat analysis from the study's raw data. Reanalysis found no difference in prostate-cancer–specific mortality between the two groups at 11-year follow-up.
The second trial recruited men 50 to 69 years of age from Norrkoping, Sweden, from the national population register. A total of 9,026 men were identified, with one in six invited to screening (1,494 invited; 7,532 not invited). Exclusion criteria were not reported. Screening was performed every three years by DRE alone or by DRE and PSA testing. Of those invited for screening, 70 to 77 percent were screened. There were no data on how many uninvited men received screening. In the intention-to-treat analysis, there was no difference between the two groups in prostate-cancer–specific death at 15-year follow-up.
There are two ongoing large-scale RCTs of prostate cancer screening: the European Randomised study of Screening for Prostate Cancer trial and the Prostate, Lung, Colorectal and Ovarian cancer screening trial. It is anticipated that findings from these two trials will be available in the next few years and will provide the evidence needed to determine whether screening for prostate cancer should be offered routinely. In the meantime, shared decision making—including a discussion of the false-positive and false-negative results of screening tests, the variable natural history of prostate cancer in various individuals, and the uncertainty of the net benefit of early detection and treatment in asymptomatic men—has been recommended by major professional organizations.1–3