Should You Pass on Getting a Rectal Exam to Screen for Prostate Cancer?
This year alone, the American Cancer Society estimates that 29,430 men will die from prostate cancer, which trails only lung cancer as a leading cause of cancer death in men.
The abnormal growth of cells begins in the cancer's namesake walnut-sized gland in the male reproductive system -- and that's frequently where it stays. Despite the high absolute death toll, experts often point out that, in relative terms, many more men die with prostate cancer than die from it. "Prostate cancer can be a serious disease, but most men diagnosed with prostate cancer do not die from it," the American Cancer Society notes. "In fact, more than 2.9 million men in the United States who have been diagnosed with prostate cancer at some point are still alive today." Even so, clinicians say its status as a major killer cannot be ignored.
But debate swirls around screening and treatment of the cancer, in part because of the variation in how slowly -- or quickly -- it may spread, and limitations in screening tools used. Often a prostate-specific antigen, or PSA, test is used to screen for prostate cancer, to check for high levels of the protein produced in the prostate in the blood, which may indicate that a man has prostate cancer. In addition, doctors frequently perform what's called a digital rectal exam to check the prostate; it's not high tech, and can be uncomfortable. In the routine exam, the doctor inserts a gloved finger into the patient's rectum, in this case to check the gland that's right in front of the rectum, between a man's penis and bladder, for palpable abnormalities.
[See: 10 Things Younger Men Should Know About Prostate Cancer.]
Both urologists and primary care doctors frequently perform DREs to screen for prostate cancer, as well as to check for other problems or conditions, such as rectal cancer. But just as the reliability and usefulness of the PSA test is the subject of much debate, so, too, is the use of the DRE as a screening tool for prostate cancer -- particularly in primary care, which was the focus of a research review and meta-analysis published in the March/April Annals of Family Medicine. "We found that there is a lack of evidence to support the use of DRE in routine screening for prostate [cancer] in the primary care setting," said Dr. Leen Naji in an email. She is a family medicine resident at McMaster University in Hamilton, Ontario, who led the research.
Given the variation in guidelines on prostate cancer screening in Canada and the U.S., it can be difficult for doctors and patients to determine what might be the best course of action. "It's hard as a physician to have an educated discussion with patients about a topic when the guidelines are controversial themselves," Naji says. "With this being the first and newest systematic review on the topic of using DRE in screening for prostate cancer in primary care, it will provide an objective basis for guidelines to cite when making recommendations, rather than relying on expert opinion or individual studies," she asserts.
Rather than being used to conclusively diagnose prostate cancer (where a biopsy is commonly done to confirm a suspected malignancy), a rectal exam involves checking for irregularities in the size, shape or texture of the gland that may suggest prostate cancer is present. Still, the researchers noted that in the majority of instances where a DRE suggested cancer might be present, a biopsy determined it wasn't. "In other words, the DRE finding in 59 percent of the men was a false positive," Naji says. While researchers didn't study the possible harms of DRE, they point out that "Some evidence suggests ... the DRE may not significantly reduce mortality, but instead may result in a high number of false-positives leading to unnecessary invasive diagnostic tests that can precipitate pain, erectile dysfunction, and urinary incontinence, as well as overdiagnosis and overtreatment of prostate cancer."
However, they don't suggest throwing out the DRE altogether. "Many have interpreted our research to conclude that the DRE is a useless test. But that is not what we are suggesting," Naji emphasizes. "What we found is that there is simply no evidence to support its use in primary care for prostate cancer screening, and that we therefore do not recommend its routine use for that purpose." They didn't review research on its use in other clinical settings or as a means to check on other potential health issues. "There are still other uses for the DRE (e.g. in a urologist's office, in the case of major traumas, or rectal bleeding)," she says.
Though many primary care physicians may be well-versed in using DRE, research indicates some PCPs may doubt their ability to detect prostate abnormalities that signal cancer might be present: "Only one-half of surveyed primary care physicians reported feeling confident in their ability to detect prostate nodules using DRE," the researchers noted. Although they were unable to study whether doctor specialty might make a difference in DRE effectiveness, it may be that urologists -- given added training and experience with the male reproductive tract -- are better equipped to perform a DRE and interpret their findings, though certainly not everyone -- including primary care doctors -- agree with this. Family physicians and internists also have many responsibilities competing for their attention in a short visit, like staying up on continually evolving recommendations in many other areas from blood pressuring monitoring to screening for high cholesterol. "It's not a criticism of primary care physicians -- they have many, many things on their plate," says Dr. Edward Schaeffer, chair of urology at Northwestern Memorial Hospital and a professor of urology at Northwestern University in Chicago. So I understand why the data suggests it's not a good test in the hands of ... a primary care physician, but I don't think that means that the test is a bad test. If you ask me to interpret an echocardiogram, I couldn't do it."
[See: 10 Questions to Ask Your Doctor About Prostate Cancer.]
As far as DREs, he says that's something he does as part of a physical exam. "If you're seeing a patient, I feel like you should examine a patient. So," as a urologist he says, "I do it routinely for all my patients."
But a standard recommendation for DRE as a means of screening men for prostate cancer is hard to come by. At present, the American Urological Association doesn't offer specific recommendations on DRE, due to a dearth of data. "While there are several potential tests that could be applied in screening for prostate cancer, almost all currently available data pertain to the use of PSA with or without DRE," the AUA notes in its Early Detection of Prostate Cancer Clinical Guideline. "As a primary screening test, there is no evidence that DRE is beneficial, but DRE in men referred for an elevated PSA may be a useful secondary test."
Instead, experts generally suggest men talk it over with their doctors. The American Cancer Society "recommends that men have a chance to make an informed decision with their health care provider about whether to be screened for prostate cancer. The decision should be made after getting information about the uncertainties, risks, and potential benefits of prostate cancer screening," the ACS states. "Men should not be screened unless they have received this information."
Men who have a high risk of developing prostate cancer -- including African-Americans and men with a first-degree relative (father, brother or son) who's been diagnosed with prostate cancer before the age of 65 should start the screening discussion at age 45, the ACS says; those at even higher risk -- with more than one first-degree relative who had prostate cancer -- should begin the screening discussion at age 40. Men of average risk should start it at age 50, according to the ACS. After talking it over, men who want to be screened should be tested with a PSA blood test; and the DRE may also be done as part of screening, the organization says.
John Cullen, president-elect of the American Academy of Family Physicians, says the recommendations coming out of the latest research analysis published in the Annals of Family Medicine reflect the AAFP's position on DRE for prostate cancer screening. "We are not recommending testing for prostate cancer, either with digital rectal exam or PSA at this point," Cullen says. "The reason is that the problem with testing -- for both PSA testing and digital rectal exam -- is that the risk of false positives is quite high."
[See: 8 Possible Signs of Testicular Cancer.]
But proponents of routine screening for prostate cancer argue that screening remains a man's best chance to detect prostate cancer early, and treat it. Critics, on the other hand, say screening doesn't do a good job differentiating between aggressive, deadly cancers, which can also still be missed, from slow-growing ones. "Even though prostate cancer is one of the most common forms of cancer ... for many people, it actually doesn't do anything," Cullen says.
Ultimately, most experts say the key is for men to talk over the potential risks and benefits of prostate cancer screening, including with DRE, with their doctor before making their own decision.
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