Screening is testing to find cancer in people before they have symptoms. For some types of cancer, screening can help find cancers at an early stage, when they are likely to be easier to treat.
Prostate cancer can often be found early by testing for prostate-specific antigen (PSA) levels in a man’s blood. Another way to find prostate cancer is the digital rectal exam (DRE). For a DRE, the doctor puts a gloved, lubricated finger into the rectum to feel the prostate gland. These tests and the actual process of screening are described in more detail in Screening Tests for Prostate Cancer.
If the results of either of these tests is abnormal, further testing (such as a prostate biopsy) is often done to see if a man has cancer.
Concerns about prostate cancer screening
If prostate cancer is found as a result of screening, it will probably be at an earlier, more treatable stage than if no screening were done. While this might make it seem like prostate cancer screening would always be a good thing, there are still issues surrounding screening that make it unclear if the benefits outweigh the risks for most men.
Possible inaccurate or unclear test results
As an example, neither the PSA test nor the DRE is 100% accurate. These tests can sometimes have abnormal results even when a man does not have cancer (known as a false-positive result), or normal results even when a man does have cancer (known as a false-negative result). Unclear test results can cause confusion and anxiety. False-positive results can lead some men to get prostate biopsies (with small risks of pain, infection, and bleeding) when they don’t have cancer. And false-negative results can give some men a false sense of security even though they might actually have cancer.
Overdiagnosis and overtreatment
Another important issue is that even if screening detects prostate cancer, doctors sometimes can’t tell if the cancer is truly dangerous (and therefore needs to be treated). Finding and treating all prostate cancers early might seem to make sense, but some prostate cancers grow so slowly that they would never cause a man problems during his lifetime.
Because of screening, some men may be diagnosed with a prostate cancer that they would have never known about otherwise. It would never have led to their death, or even caused any symptoms. Finding a ‘disease’ like this that would never cause problems is known as overdiagnosis.
A problem with overdiagnosis in prostate cancer is that many of these men might still be treated with either surgery or radiation, either because the doctor can’t be sure how quickly the cancer might grow and spread, or because the man is uncomfortable knowing he has cancer and is not getting any treatment. Treatment of a cancer that would never have caused any problems is known as overtreatment. The major downside with this is that even if they weren’t needed, treatments like surgery and radiation can still have urinary, bowel, and/or sexual side effects that can seriously affect a man’s quality of life.
Men and their doctors may end up struggling to decide if treatment is needed or if the cancer can just be closely watched without being treated right away (an approach called watchful waiting or active surveillance). Even when men are not treated right away, they still need regular blood PSA tests and prostate biopsies to determine their need for treatment in the future. These tests are linked with risks of anxiety, pain, infection, and bleeding.
Benefits of screening in studies have not been clear
Doctors are still studying if screening tests will lower the risk of death from prostate cancer. The most recent results from 2 large studies were conflicting, and didn’t offer clear answers.
- Early results from a large study done in the United States found that annual screening with PSA and DRE did detect more prostate cancers than in men not screened, but this screening did not lower the death rate from prostate cancer. However, questions have been raised about this study, because some men in the non-screening group actually were screened during the study, which might have affected the results.
- A European study did find a lower risk of death from prostate cancer with PSA screening (done about once every 4 years), but the researchers estimated that about 781 men would need to be screened (and 27 cancers detected) to prevent one death from prostate cancer.
- Neither of these studies has shown that PSA screening helps men live longer overall (that is, that it lowers the overall death rate).
- Prostate cancer is often slow-growing, so the effects of screening in these studies might become clearer in the coming years. Both of these studies are being continued to see if longer follow-up will give clearer results. Prostate cancer screening is being studied in several other large studies, as well.
For now, the American Cancer Society recommends that men thinking about getting tested for prostate cancer learn as much as they can so they can make informed decisions based on available information, discussions with their doctor, and their own views on the possible benefits, risks, and limits of prostate cancer screening. (See American Cancer Society Recommendations for Prostate Cancer Early Detection.)
Until more information is available, you and your doctor should decide whether you should be screened for prostate cancer. There are many factors to take into account, including your age, health, and family history. For example, if you’re young and develop prostate cancer, it may shorten your life if it’s not caught early. Screening men who are older or in poor health is less likely to help them live longer. This is because most prostate cancers are slow-growing, and men who are older or have major health problems are more likely to die from other causes before their prostate cancer grows enough to cause problems.