What is the PSA screening controversy?
The goal of measuring PSA in men with no symptoms of cancer as a screening test for prostate cancer is to reduce the mortality caused by this cancer. Although the advent of prostate cancer screening is associated with decreased prostate cancer deaths, concerns exist regarding risks of overtreatment and the associated risks of such treatments.
A substantial number of the cancers detected by PSA screening are early stage and low-risk, and these patients will likely never die from this disease. PSA screening, due to its low specificity, does not allow differentiating between low-risk and high-risk prostate cancer. Hence PSA systematic screening is inevitably associated with over-diagnosis and potentially overtreatment. Therefore, not only do these patients not benefit from early detection but they also carry the burden of a cancer diagnosis. In addition, a subset of these patients may suffer the side effects of an unnecessary treatment.
One large European trial (ERSPC) found that PSA screening significantly reduces the mortality (death rate) of prostate cancer but is also associated with a high risk of over-diagnosis. The cumulative incidence of prostate cancer was 8.2% in the PSA screening group and 4.8% in the control group. Patients in the screening group were 20% less likely to die from prostate cancer compared with the control group. The absolute risk difference between the two groups was 0.71 deaths per 1,000 men. This means that to prevent one death from prostate cancer, 1,410 men would need to be screened with PSA testing and 48 additional cases of prostate cancer would need to be treated.
Another trial (PLCO) conducted in the United States recently concluded that there is no evidence of an improvement in death rate from prostate cancer with annual PSA screening compared with usual medical care. After 13 years of follow-up, the cumulative mortality rates from prostate cancer in the intervention and control groups were 3.7 and 3.4 deaths per 10,000 person-years, respectively, meaning that there was no significant difference between the two groups.
Based on the results of the PLCO trial, the U.S. Preventive Service Task Force (USPSTF) initially advised against PSA screening in their draft recommendation issued in 2011. More recently, the USPSTF issued a draft of revised recommendations that await finalization. This draft statement reports that the decision about whether to be screened for prostate cancer should be an individualized one. That USPSTF recommended individualized decision-making about screening for prostate cancer after discussion with the physician so that each man has the opportunity to understand the potential benefits and harms of screening and to incorporate his values and preferences into his decision.
Several urological associations, including the American Urological Association (AUA), Canadian Urological Association (CUA), and European Urological Association (EAU), still value the benefit of PSA screening and recommend physician-patient discussions about screening on an individual basis. The American Urological Association guidelines currently do not recommend routine prostate cancer screening in men between the ages of 40 and 54 years who are felt to be at average risk. For men less than 55 years of age at higher risk (for example, family history of prostate cancer, African-American race), decisions regarding prostate cancer screening should be individualized. The guidelines panel recommends shared decision-making for men 55-69 years of age who are considering prostate cancer screening. Furthermore, the panel notes that to reduce the harms of screening a routine screening interval of two years or more may be preferred over annual screening in those men who shared in clinical decision-making and decided on screening. Lastly, routine PSA screening was not recommended in men 70 years of age and older or any male with less than a 10- to 15-year life expectancy.
The American Cancer Society recommends that asymptomatic men (with no symptoms) who have at least a 10-year life expectancy have an opportunity to make an informed decision with their health care provider about screening for prostate cancer after they receive information about the uncertainties, risks, and potential benefits associated with prostate cancer screening. Prostate cancer screening should not occur without an informed decision-making process. Men at average risk should receive this information beginning at 50 years of age. Men in higher risk groups should receive this information before 50 years of age.
The National Comprehensive Cancer Network (NCCN) guidelines for early detection of prostate cancer noted that most panel members favored informed prostate cancer screening, in men with 10 or more year life expectancy, beginning at age 45 years of age. The panel recommended testing at one- to two-year intervals for men with a PSA of > 1.0 ng/ml and every two to four years for those with PSA < 1 ng/mL.