People often get confused about the difference between screening for prostate cancer and early detection of the disease. It happens to professionals and to patients. Let’s see if we can help to make the difference clear.
The Brownsville Experiment
Dr Brown, a urologist, wants to find how many men in Brownsville have prostate cancer.
The first year — Dr Brown decides that in order to answer his question he will give a free digital rectal examination (DRE) and PSA test to every fifth man over 40 years old who walks past his office on main street on a Saturday morning in May. In other words, these men are picked completely at random — except that they must walk past his office and be over 40. This is a true prostate cancer screening program. The men don’t necessarily even think that they should be having a prostate cancer test.
The second year — A screening program like the one he does in the first year takes a lot of effort, so the next year Dr Brown decides just to offer a free DRE and PSA test to any man over 40 who comes to his office on the same Saturday morning in May and asks to be tested. So he puts an ad in his local Brownsville newspaper. This year, the people who get the DRE and the PSA test have selected themselves for some reason. Maybe they just think its time they had a PSA test. Maybe they have had to get up a few times too often in the middle of the night. Maybe their wife told them it was high time they had a prostate cancer test. Or maybe they just thought that they’d have the tests while they were free. Some physicians now call this case finding. It certainly isn’t screening, because the tests aren’t being given at random and the men who get the tests have selected themselves.
The third year — Finally, the third year, Dr Brown decides he isn’t going to give anything away for free. Instead, he will encourage every man over 40 who comes to his office to have a DRE and a PSA test, regardless of their symptoms. His justification for this is that if they have come to see him — a urologist — there is good reason to think that they may have a urological disorder, including prostate cancer. This is true early detection. In other words, Dr Brown is going to do his best to find prostate cancer in any patient who comes to see him, but he isn’t going to go out of his way to look for patients with the disease.
Recommendations for Prostate Cancer Testing
There is now some information that suggests that screening for prostate cancer can make a difference to how long men in a defined population will live if they are all regularly tested for prostate cancer. Studies completed in the Tyrol region of Austria and in King County, Washington in the USA provide evidence for the possible benefits of population screening.
For comparison, we have known for many years that screening women for breast cancer (using breast self examination and mammograms to detect breast cancer early) does indeed make a difference to the survival of at least some patients with this disease. The same is true for colon cancer (using fecal blood monitoring and colonoscopies). However, the majority of the American (and indeed the world’s) population still do not get regular, recommended screening tests for either of these forms of cancer.
A major clinical trial being carried out by the National Cancer Institute (the so-called PCLO trial ) has, as one of its objectives, the determination of whether prostate cancer screening will increase patient survival. The full results of this trial are still not available yet, and some people are not convinced that the way this trial has been organized will allow us to find the information we are looking for. However, some data from this trial are available.
Recommendations of the US Preventive Services Task Force — In the most recent (December 2002) revision to its guidelines on prevention of prostate cancer, the US Preventive Services Task Force indicated that “the evidence is insufficient to recommend for or against routine screening for prostate cancer using prostate specific antigen (PSA) testing or digital rectal examination (DRE).”
This does not mean that men with possible symptoms of prostate cancer should not be tested. It does mean that a large sector of the medical community still does not endorse annual PSA tests and DREs for asymptomatic males.
In their summary rationale for this decision the Task Force states as follows:
The USPSTF found good evidence that PSA screening can detect early-stage prostate cancer but mixed and inconclusive evidence that early detection improves health outcomes. Screening is associated with important harms, including frequent false-positive results and unnecessary anxiety, biopsies, and potential complications of treatment of some cancers that may never have affected a patient’s health. The USPSTF concludes that evidence is insufficient to determine whether the benefits outweigh the harms for a screened population.
The “New” Prostate Cancer InfoLink is of the opinion that it will require clear proof of an association between early disease detection and increased overall survival to change the recommendations of the US Preventive Services Task Force.
Recommendations of the American College of Physicians — The American College of Physicians (one of the largest organizations of primary care physicians in the US) published a series of detailed articles on prostate cancer in the Annals of Internal Medicine in early 1997. They made two specific recommendations in their clinical guidelines on screening:
Recommendation 1: Rather than screening all men for prostate cancer as a matter of routine, physicians should describe the potential benefits and known harms of screening, diagnosis, and treatment; listen to the patient’s concerns; and then individualize the decision to screen.
Recommendation 2: The College strongly recommends that physicians help enroll men in ongoing studies.
This second recommendation is a specific reference to the PLCO screening trial previously mentioned and the PIVOT trial (which is discussed elsewhere).
It should be noted, however, that the ACP states clearly on their web site that any guideline that is more than 5 years old is considered to be outdated. Their guidelines on prostate cancer are now 11 years old.
Recommendations of the American Urological Association — The American Urological Association (the AUA) is the national organization representing most of the urologists in America. This group currently makes the following recommendations regarding early detection of prostate cancer:
“Both prostate specific antigen (PSA) and digital rectal examination (DRE) should be offered annually, beginning at age 50 years, to men who have a life expectancy of at least 10 years.”
“Men at high risk (those with a family history of prostate cancer or African American men) should consider beginning testing at an earlier age.”
“Information should be provided to patients about benefits and limitations of testing.”
“Men who desire to learn more about benefits and limitations of testing for early detection and treatment of prostate cancer should be counseled regarding the availability of resources to aid them in their decision-making.”
“Further evaluation of a man undergoing prostate cancer screening with digital rectal examination and PSA should incorporate other known risk factors including family history of prostate cancer, age, ethnicity/race, and whether the individual has had a prior negative prostate biopsy.”
“The risk of cancer if biopsy is performed, the health and life expectancy of the man, and his personal preferences should be incorporated in the decision to perform further evaluation, generally with a prostate biopsy.”
These recommendations were last updated in May 2006.
Recommendations of the American Cancer Society — The American Cancer Society (ACS) has issued guidelines which are close to those of the AUA on prostate cancer screening. According to the ACS:
Both the prostate-specific antigen (PSA) blood test and digital rectal examination (DRE) should be offered annually, beginning at age 50, to men who have at least a 10-year life expectancy.
Men at high risk (African-American men and men with a strong family of one or more first-degree relatives [father, brothers] diagnosed before age 65) should begin testing at age 45.
Men at even higher risk, due to multiple first-degree relatives affected at an early age, could begin testing at age 40. Depending on the results of this initial test, no further testing might be needed until age 45.
The ACS states further that:
Information should be provided to all men about what is known and what is uncertain about the benefits, limitations, and harms of early detection and treatment of prostate cancer so that they can make an informed decision about testing.
Men who ask their doctor to make the decision on their behalf should be tested. Discouraging testing is not appropriate. Also, not offering testing is not appropriate.
Should You Have Regular Prostate Cancer Tests?
As indicated in the recommendations of the US Preventive Services Task Force, and despite the recommendations of the AUA and the ACS, there are many physicians who do not believe that annual PSA tests are necessarily a good thing. They argue that while it may be possible to find indications of possible prostate cancer using digital rectal examinations and PSA tests, the really difficult questions are:
How hard must we then search to discover whether a particular patient actually has prostate cancer?
How should we treat his disease when we find it?
An option that some men consider is annual DREs without PSA testing. While there is a good chance that such tests will allow an experienced urologist to detect clinically significant prostate cancer, it is also true that by the time a DRE becomes a certain indicator of probable prostate cancer, it may not be possible to apply potentially curative therapy with confidence.
Ultimately the decision whether you should have regular tests for prostate cancer — and what those tests should be — is a matter for you and your physician. The answer is likely to require careful assessment of your personal attitudes to the risks of cancer, family history of cancer, age, and your other clinical history.
The “New” Prostate Cancer InfoLink encourages you to talk frankly with your primary care physician about this and to make your decision only when you feel comfortable about it.
The American College of Physicians has specifically recommended that all men who are considering having a DRE and a PSA test should be fully informed as follows:
Prostate cancer is an important health problem.
The benefits of one-time or repeated screening and aggressive treatment of prostate cancer have not yet been proven.
Digital rectal examination and PSA measurement can both have false-positive and false-negative results.
The probability that further invasive evaluation will be required as a result of testing is relatively high.
Aggressive therapy is necessary to realize any benefit from the discovery of a tumor.
A small but finite risk for early death and a significant risk for chronic illness, particularly with regard to sexual and urinary function, are associated with these treatments.
Early treatment may save lives.
Early detection and treatment may avert future cancer-related illness.
Another issue that presents challenges is the relevance of continued annual testing for prostate cancer in men over the age of 75 years. Some proposals for how to address this issue have recently been put forward in the so-called “ Iowa Prostate Cancer Consensus.”