The word screening refers to testing to find a disease like cancer in people who do not have symptoms of that disease. For some types of cancer, screening can help find cancers in an early stage when they are more easily cured. The goal of screening is to help people live healthier, longer lives.
The goal of screening for prostate cancer is to find it early, in the hope that it can be treated more effectively.
Prostate cancer can often be found early by testing the amount of prostate-specific antigen (PSA) in your blood. Another way to find prostate cancer early is the digital rectal exam (DRE). For this exam, your doctor puts a gloved finger into the rectum to feel the prostate gland. These 2 tests are described in more detail in the section, "What tests can detect prostate cancer?"
If prostate cancer is found during screening with the PSA test or DRE, your cancer will likely be at an early, more treatable stage than if no screening were done.
Since using early detection tests for prostate cancer became relatively common (about 1990), the prostate cancer death rate has dropped. But it isn't clear yet that this drop is a direct result of screening. It could also be caused by something else, like improvements in treatment.
There are limits to prostate cancer screening tests used today. Neither the PSA test nor the DRE is 100% accurate. These tests can have abnormal results even when cancer is not present (known as false positive results). In addition, normal results can occur even when cancer is present (known as false negative results). Unclear test results can cause confusion and anxiety. False positive results can lead some men to undergo a prostate biopsy (with small risks of pain, infection, and bleeding) when cancer is not present. And false negative results may give some men a false sense of security even though they actually have cancer.
There is no question that the PSA test can help spot many prostate cancers early, but it's important to know that this test can't tell how dangerous the cancer is. Finding and treating all prostate cancers early may seem like a no-brainer. But some prostate cancers grow so slowly that they would likely never cause problems. Because of an elevated PSA level, some men may be diagnosed with a prostate cancer that they would have never even known about at all -- it would never have lead to their death or even caused any symptoms. But they may still be treated for these cancers, either because the doctor can't be sure how aggressive (fast growing and fast spreading) the cancer might be, or because the men are uncomfortable not having any treatment. Treatments like surgery and radiation can have side effects that may seriously affect a man's quality of life. These treatments can lead to urinary, bowel, and/or sexual problems. In some men these problems may be minimal and/or short-term, but for others these problems can be severe and long-lasting (or even permanent). Doctors and patients are still struggling to decide who should receive treatment and who might be able to be followed without being treated right away (an approach called watchful waiting or active surveillance). Even when patients are not treated right away, they still need regular blood tests and prostate biopsies to determine the need for future treatment. These tests are linked with risks of anxiety, pain, infection, and bleeding.
Studies are being done to try to figure out if early detection tests for prostate cancer in large groups of men will lower the prostate cancer death rate. The most recent results from 2 large studies were conflicting, and didn't offer clear answers.
Early results from a study done in the United States found that annual screening with PSA and DRE did detect more prostate cancers, but this screening did not lower the death rate from prostate cancer. 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 1,400 men would need to be screened (and 48 treated) in order to prevent one death from prostate cancer. Neither of these studies has shown that PSA screening helps men live longer (lowered the overall death rate).
Recently, early results of a Swedish study of prostate cancer screening were published. One group of men was offered PSA testing every other year, with follow-up tests including biopsy if the PSA was over a certain level. This study did not test elderly men - those over 71 years old were not tested. Cancer and death rates in the group offered testing were compared to a group of men who were not offered testing. After 15 years, the group that was offered testing had a lower risk of death from prostate cancer, but the overall death rate was the same in both groups.
Prostate cancer tends to be a slow growing cancer, so the effects of screening in these studies may become clearer in the coming years. Both of these studies are being continued to see if longer follow-up will give clearer results.
At this time, the American Cancer Society recommends that men thinking about prostate cancer screening should make informed decisions based on available information, discussion with their doctor, and their own views on the benefits and side effects of screening and treatment. (See the section called "American Cancer Society recommendations for prostate cancer early detection.")
Until more information is available, you and your doctor can decide whether you should have tests to screen for prostate cancer. There are many factors to take into account, including your age and health. 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 in order to find early prostate cancer is less likely to help them live longer. This is because most prostate cancers are slow-growing and men who are older or sicker are likely to die from other causes before their prostate cancer grows enough to cause problems.
Last Medical Review: 12/01/2010
Last Revised: 06/24/2011
Taken from the American Cancer Society: http://www.cancer.org/Cancer/ProstateCancer/MoreInformation/ProstateCancerEarlyDetection/prostate-cancer-early-detection-why-find-early