Prostate cancer screening is quick and easy: a digital rectal exam allows the doctor to feel the prostate and detect unusually firm or irregular areas that may be cancerous, and a blood test measures the level of prostate-specific antigen (PSA) in the blood.
PSA Testing: The RPCI Take
The PSA serum test is an invaluable tool for prostate cancer diagnosis that, when used intelligently, can significantly reduce the mortality rate of this disease. Since Roswell Park scientists created the PSA in the 1970s, the cure rate for prostate cancer has increased from about 4 percent to about 80 percent today.
Roswell Park physicians are well aware of the risks of over-treating this disease. We adhere to guidelines established by the National Comprehensive Cancer Network (NCCN) for prostate cancer early detection and treatment. These NCCN guidelines are developed by a diverse panel of more than 20 experts from across the country, including two of our own Roswell Park specialists, and are statements of consensus from this panel regarding scientific evidence and currently accepted approaches to diagnosis and treatment.
PSA is a protein made by both normal and cancerous prostate cells. It is found in semen and blood and can be measured with a blood test. By monitoring blood levels of PSA, it’s possible to detect prostate cancer in its earliest stages. Because PSA is produced by the body and can be used to detect disease, it is sometimes called a biological marker or tumor marker.
PSA levels are measured in terms of units per volume of fluid tested or nanograms per milliliter, written as ng/mL.
What do the numbers mean?
- 2.5 ng/mL or lower: A normal PSA level for men under 60, but in a minority of cases, prostate cancer may still be present.
- Between 2.5 and 4 ng/mL: A normal PSA level to most men in their 60s.
- Between 4 and 10 ng/mL: Suggests the possibility of prostate cancer. At these levels, there is approximately a 25 percent chance that you have prostate cancer.
- Above 10 ng/mL: There is a 50 percent chance that prostate cancer is present. The higher the PSA rises above 10 ng/mL, the greater the chance that you have prostate cancer.
Your doctor may also monitor your PSA velocity, which means looking at the rate of change in your PSA levels over time. Rapid increases in PSA readings can suggest cancer. If you have a mildly elevated PSA, you and your doctor may choose to check PSA levels on a scheduled basis and watch for any change in the PSA velocity.
PSA levels can be used with clinical examination results and the tumor’s Gleason score to help determine which tests are needed for further evaluation and to decide upon the best treatment plan. After treatment has begun, PSA is used to monitor the effects of therapy — the more successful the therapy, the lower the PSA.
PSA levels can rise for reasons other than prostate cancer, including aging, infection, the use of certain herbal supplements, and an enlarged prostate (not due to cancer). Some prostate glands naturally produce more PSA than others; African-American men tend to have higher PSA levels than men of other races. Your PSA level may also increase after ejaculation or bicycling, so doctors advise men to refrain from both for at least two days prior to a PSA exam.
NCCN Prostate Cancer Screening Guidelines
The most recent recommendations for prostate cancer screening are as follows:
- Men interested in screening should receive a baseline PSA test and digital rectal exam at age 40 that can be used for comparison with future tests. If they have a PSA of 1.0 ng/mL or greater, they should receive annual follow-ups. If PSA is less than 1.0 ng/mL, they should have a follow-up screening at age 45.
- Men who are at high risk of developing prostate cancer — African-Americans, those with a family history (a father or brother diagnosed, especially if they were younger than age 65), or those with a confirmed BRCA1 or BRCA2 genetic mutation — should begin screening at age 40 (or 10 years prior to age of earliest prostate cancer case in family) and continue regularly.
- Regular screening should be offered to all men beginning at age 50.
- Older men (over age 75) or those with a life expectancy of less than 10 years should elect to discontinue PSA screening.
A patient’s age, life expectancy, family history, race and previous early detection results should be considered on a case-by-case basis prior to determining a screening program. Patients are encouraged to discuss the pros and cons of a screening regimen with their physicians.
Digital Rectal Exam
In addition to the PSA test, screening for prostate cancer includes a digital rectal exam or DRE. Most prostate cancers begin in the part of the gland that is nearest the rectum and can be reached by a rectal exam.
This exam is also used once a man is known to have prostate cancer in order to help predict whether the cancer has spread beyond his prostate gland.