Prostate cancer is the most common form of cancer after skin cancer among men in the United States, and it is second only to lung cancer as a cause of cancer-related death among men. It is estimated that more than 230,000 men in the U.S. will be diagnosed with prostate cancer this year.

Many types of prostate cancer grow very slowly. So even without treatment, many men with prostate cancer will not die from the disease, but from some other, unrelated cause. However, about 30,000 U.S. men die of prostate cancer each year.

Prostate Cancer Screening Tests

Prostate-Specific Antigen (PSA) Blood Test: Prostate-specific antigen (PSA) is a substance made by the normal prostate gland. Most men have levels under 4 nanograms per milliliter (ng/mL) of blood. Men with PSA levels between 4 and 10 have about a 25 percent chance of having prostate cancer. The chances that a man with a PSA level above 10 has prostate cancer are about two in three.

However, PSA levels can be affected by other factors, such as age and benign enlargement or inflammation of the prostate gland. PSA testing may yield false positive or false negative results. It may identify slow-growing tumors unlikely to threaten a man’s life, or reveal an aggressive cancer that has already spread to other parts of the body before being detected. Therefore, the results of a PSA test alone do not definitively prove the existence of prostate cancer.

Digital Rectal Exam (DRE): During this exam, a doctor inserts a gloved, lubricated finger into the rectum to feel for any irregular or firm area that might be a cancer. The prostate gland is located just in front of the rectum, and most cancers begin in the back part of the gland, which can be reached by a rectal exam.

Doctors often use a combination of the PSA test and DRE as prostate cancer screening tests; together, these tests can help detect "silent" prostate cancer in men who have no symptoms of the disease. A diagnosis of prostate cancer can be confirmed only by a biopsy.

If a man’s PSA levels have been increasing or if a suspicious lump is detected during the DRE, the doctor may recommend other tests to determine if there is cancer or another problem in the prostate, such as a urinary tract infection. These tests might include imaging tests such as ultrasound (a test in which high-frequency sound waves are used to obtain images of the kidneys and bladder), x-rays, or cytoscopy (a procedure in which a doctor looks into the urethra and bladder through a thin, lighted tube).

Transrectal Ultrasound (TRUS) uses high-frequency sound waves to make an image of the prostate on a video screen. TRUS is most commonly used during a prostate biopsy to guide the biopsy needle into exactly the right area of the prostate.

Benefits of Screening for Prostate Cancer

There is good evidence that PSA screening can detect early-stage prostate cancer. Since the use of early detection tests for prostate cancer has become relatively common over the past several years, the prostate cancer 5-year survival rate has climbed to about 97 percent. Yet because evidence is mixed and inconclusive about whether early detection improves health outcomes, there is no scientific consensus that such screening is beneficial.

However, if a man has routine yearly examinations and either one of these test results becomes abnormal, any prostate cancer he might have has probably been found at an early, more treatable stage.

Recommendations for Prostate Cancer Screening

Many, though not all, physicians and organizations encourage yearly screening for men over age 50. Some advise men who are at a higher risk for prostate cancer to begin screening at age 40 or 45.

Men at high risk for prostate cancer due to factors such as ethnicity (African-American men are at higher risk for prostate cancer) or a strong family history of the disease should talk with their doctors about beginning screening earlier, at age 40 or 45.

Other PSA tests

Several newer types of PSA tests may be used if a regular PSA test reveals higher-than-normal PSA blood levels to help determine if a prostate biopsy is needed.

Percent-free PSA: PSA occurs in two major forms in the blood. One is attached to blood proteins and the other circulates free. The percentage of free PSA is lower in men who have prostate cancer than in men who do not.

PSA velocity: The PSA velocity measures the change in PSA values over time. Even when the total PSA value isn’t over 4 ng/mL, a high PSA velocity suggests that cancer may be present and a biopsy should be considered.

PSA density: The PSA density (PSAD) is used for men with large prostate glands. The doctor determines the volume of the prostate gland with transrectal ultrasound and divides the PSA number by the prostate volume. A higher PSA density (PSAD) indicates greater likelihood of cancer.

Age-specific PSA ranges: Because PSA levels are normally higher in older men than in younger men, some doctors have suggested comparing PSA results with results from other men of the same age.