Prostate cancer is the number one cancer in men and the second leading cause of cancer deaths for men in the United States, after lung cancer.¹ There were about 186,000 new cases of prostate cancer in the U.S. in 2008, and more than 28,000 men are estimated to have died of the disease that year.² One in every six men will be diagnosed with prostate cancer in their lifetime,³ with about 90% of cases occurring in men 55 and older,⁴ and 71% of deaths in men over 75.⁵ This is why screening is only recommended for men over 50. Prostate cancer grows very slowly. Even without treatment, many men with prostate cancer will live with the disease until they eventually die of some other, unrelated cause.

The two screening methods for prostate cancer are the prostate-specific-antigen (PSA) test, which tests for high levels of that antigen in the blood, and the digital rectal exam (DRE), which searches for abnormalities in the rectum. Neither of the screening tests for prostate cancer is 100% accurate. Most men with a high PSA level (<4ng/mL) do not have prostate cancer (this is known as a false positive), and some men with prostate cancer have a low PSA level (this is called a false negative). The DRE also results in many false positives and false negatives. Using both screening methods together will miss fewer cancers but also increases the number of false positives, which can lead to more testing and possibly result in medical complications. These complications are primarily infection, bleeding, clot formation, and urinary difficulties.⁶ Treatments for prostate cancer can cause serious and chronic problems, such as urinary incontinence and impotence.⁶ Since the disease is rarely fatal, many doctors and patients question whether annual prostate cancer screenings (or the treatment that is recommended following diagnosis) are a good idea.

New Research Findings in 2009 from Two Trials

The Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial was a large-scale clinical trial carried out by the National Cancer Institute (NCI), which is part of the National Institutes of Health.⁷ The main objective of the program was to evaluate the ability of screening tests to reduce deaths from these four common cancers.

More than 76,000 men at 10 different centers throughout the U.S. were randomly assigned to either receive annual screenings or to be in a control group in which participants continued with their usual regimen of care, which may or may not have included some screening. The men in the screening group were checked for prostate cancer using a Prostate-Specific Antigen (PSA) at the initial visit, and then annually for 6 years. They were also given a Digital Rectal Exam (DRE) at the initial visit and annually for 4 years.⁶

The trial followed men for 7-10 years and found a low death rate from prostate cancer, and most importantly no significant difference in the death rate between the men who were regularly screened and those who received their usual care.⁶ These preliminary results challenge the assumptions behind recommendations for annual prostate cancer screenings and are also providing an incentive for researchers to improve the PSA test.

While the U.S. trials conducted by the National Cancer Institute show little to no benefit from annual prostate screening, data from an even larger study conducted in Europe, more or less during the same period, indicate that PSA screening every four years without DRE reduces prostate cancer mortality by about 20%.⁸ The European Randomized Trial of Screening for Prostate Cancer (ERSPC) studied 182,000 men, ranging from 50 to 74 years old, from seven different European countries. These men were randomly assigned to either the control group, which was not offered any screenings, or to the screening group, which received PSA screening once every 4 years. PSA screenings reduced prostate cancer deaths by about 7 deaths per 10,000 men. This means that for each death prevented, a program must screen more than 1,400 men and treat an additional 48 men. ⁸ These trial results are based on a median follow up of 9 years.

What Should Men Do?

The two studies are difficult to compare, and both are continuing to follow-up on participants, so it’s too early to draw any final conclusions. On the one hand, the European trial was significantly larger, but it is really a collection of trials from different countries, each with slightly different criteria for participation and different screening and follow-up practices. Most important, men in the control groups of both studies may have also received some prostate screening, so that the studies do not compare screening with no screening, but rather more frequent screening with less frequent screening. For example, in the U.S. study, approximately half the men had at least one PSA screening during the first seven years of the study, and slightly fewer had at least one DRE. Both trials, separately and taken together, underscore important points: screening with PSA can help reduce deaths from prostate cancer somewhat, but screening invariably leads to over-diagnosis and overtreatment. In the European study, 8.2% of men in the screening group received a diagnosis of prostate cancer versus 4.8% of men from the control group. The screening group was also more than twice as likely to undergo a radical prostatectomy (removal of the prostate gland) than the screening group (2.8% of screening group vs.1.0% of men in the control group). Similarly 2.2% of men in the screening group underwent radiation therapy, while approximately 1.2% of men in the control group had radiation therapy.⁹ It is important that the reduction in deaths attributed to screening every four years (7 fewer deaths per 10,000 men) be understood in the context of approximately 340 fewer men diagnosed, 180 fewer men having their prostrate gland removed, and 100 fewer men undergoing radiation, for every 10,000 men over 50.

The Response to the Recent Research Findings

The National Cancer Institute’s (NCI) Early Detection Research Network (EDRN) has a Prostate Collaborative Group that is testing strategies aimed at developing more accurate methods of detecting prostate cancer early. Also, NCI’s prostate cancer Specialized Program of Research Excellence (SPORE) is funding projects to identify new diagnostic and prognostic biological markers, or biomarkers, of prostate cancer besides PSA.

Do the risks outweigh the benefits?

In spite of these two important, large-scale studies, we still do not have clear answers about which men, if any, should be screened and how often. The risk of complications from screenings and diagnostic procedures, and the harms from treatment, may or may not outweigh the benefits of early detection of prostate cancer. Because of these conflicting findings, recommendations vary. A family history of prostate cancer or other cancers may influence how often a man chooses to get PSA screening; however, the studies described above indicate that it is unlikely that annual screenings are a good idea. In fact, in April 2009, the American Urological Association issued new guidelines saying that annual screening was no longer recommended.

What about less frequent screening? As of August 2008, the United States Preventive Task Force position states that prostate cancer screening is not recommended for men over 75 and “the current evidence is insufficient to assess the balance of benefits and harms of prostate cancer screening in men younger than age 75 years.”⁵