The purpose of screening for cancer is to detect the cancer at its earliest stages, before any symptoms have developed.
Some men, however, will experience symptoms that might indicate the presence of prostate cancer. Because these symptoms can also indicate the presence of other diseases or disorders (such as BPH or prostatitis), these men will undergo a more thorough work-up. Typically, men whose prostate cancer is detected through screening are found to have very early-stage disease that can be treated most effectively.
Screening for prostate cancer can be performed quickly and easily in a physician's office using two tests: the PSA (prostate-specific antigen) blood test, and the digital rectal exam (DRE).
The PSA Blood Test
PSA is a protein produced by the prostate and released in very small amounts into the bloodstream. When there's a problem with the prostate, such as when prostate cancer develops and grows, more and more PSA is released, until it reaches a level where it can be easily detected in the blood.
During a PSA test, a small amount of blood is drawn from the arm, and the level of PSA is measured by nanograms per milliliter of blood. PSA levels less than 4 ng/mL are usually considered "normal," results over 10 ng/mL are usually considered "high," and results between 4 and 10 ng/mL are usually considered "intermediate." However, PSA can also be elevated if other prostate problems are present, such as BPH or prostatitis, and some men with prostate cancer have "low" levels of PSA. This is why both the PSA and DRE are used to detect the presence of disease.
According to the American Cancer Society, a PSA level between 4 and 10 indicates a 25% chance of it being prostate cancer. A PSA higher than 10 means there's at least a 50% chance its prostate cancer.
The Digital Rectal Exam
During a DRE, the physician inserts a gloved, lubricated finger into the rectum and examines the prostate for any irregularities in size, shape, and texture. Often, the DRE can be used by urologists to help distinguish between prostate cancer and non-cancerous conditions such as BPH.
Should I Be Screened?
The American Urological Association (AUA) Foundation recommends that all men over 40 should speak with their doctors at the time of their annual physicals and develop a proactive prostate health plan that is right for them based on their lifestyles and family history. The AUA also recommends getting a baseline PSA along with a DRE at age 40.
Here are some advantages and drawbacks to the PSA test that men should be aware of:
- Benefits of the PSA Test:
- Prostate cancer can be detected by the test long before symptoms present themselves.
- The test detects cancer 5 to 10 years earlier than digital rectal exams (DREs).
- Early detection before the cancer has spread outside the prostate provides men with more treatment options and a better chance for a medical cure.
- Though this is a controversial claim by some experts, the test may contribute to significant reduction deaths from prostate cancer.
- The test is a quick, simple and painless procedure involving a medical staffer taking a sample of blood for testing in a lab.
- Drawbacks of the PSA Test:
- Significant number of false negatives. In 1 out of 5 cases, the PSA test comes back 'normal' with PSA levels in men with early prostate cancer.
- High rate of false-positive results. Two out of 3 of those with elevated levels of PSA do not have prostate cancer, so the test may cause undue worry.
- A false-positive result can lead to unnecessary follow-up testing that is more invasive, i.e., multiple biopsies.
- The test does not distinguish between prostate cancer and other prostate problems such as infection and BPH - again, leading to more false positives and unnecessary follow-up procedures.
- Men over the age of 75 may not benefit from the test because the prostate is generally very slow growing and treatment is unlikely to lengthen their lives.
There is no unanimous opinion in the medical community regarding the benefits of prostate cancer screening. Those who advocate regular screening believe that finding and treating prostate cancer early offers men more treatment options with potentially fewer side effects. Those who recommend against regular screening note that because most prostate cancers grow very slowly, the side effects of treatment would likely outweigh any benefit that might be derived from detecting the cancer at a stage when it is unlikely to cause problems.
Because a decision of whether to be screened for prostate cancer is a personal decision, it's important that each man talk with his doctor about whether prostate cancer screening is right for him.