Screening & Detection
The American Cancer Society (ACS) guidelines on screening and early detection of prostate cancer recommend that a digital rectal exam (DRE) and a prostate-specific antigen (PSA) blood test should be offered annually to men beginning at age 50, for men who have a life expectancy of at least 10 years.1 However, men at increased risk of developing prostate cancer, such as African American men and men with a family history of 1 or more first-degree relatives (father, brother, or son) diagnosed with prostate cancer at an early age, should begin annual DRE and PSA testing beginning at age 45.1 Additionally, the National Comprehensive Cancer Network (NCCN) Guidelines on early detection of prostate cancer recommend that for men who choose to begin PSA screening, it is reasonable to consider obtaining a baseline PSA value at age 40.2
It is recommended that physicians discuss with their patients what is known and what is uncertain about the benefits and limitations of annual screening1,2, so men can make an informed decision.
DRE
A digital rectal examination (DRE) is a quick and safe screening technique in which a doctor inserts a gloved, lubricated finger into the rectum to feel the size and shape of the prostate (see picture below). The prostate should feel soft, smooth, and even. The doctor examines for lumps or hard, irregular areas of the prostate that may indicate the presence of prostate cancer. The entire prostate cannot be felt during a DRE, but most of it can be examined, including the area where most prostate cancers are found.
When a tumor is small and located only within the prostate, it is often not detected during a DRE. However, if an abnormality is found during the DRE, a prostate biopsy is usually suggested even if the prostate-specific antigen (PSA) level is considered normal. A biopsy is the only way to confirm the presence of prostate cancer.
Prostate-specific Antigen (PSA)
PSA is a substance produced by both normal and cancerous prostate cells. It is important to understand that PSA is not specific to the presence of prostate cancer, as other benign conditions can also cause PSA levels to increase. When prostate cancer grows or when other prostate diseases are present, the amount of PSA in the blood often increases. PSA testing can provide valuable information for your physician in determining the probability of the presence of prostate cancer and help your physician decide whether further testing or biopsy should be done to possibly rule out its presence.
Some doctors suggest that patients with a a PSA level of 4 ng/mL or above should have a prostate biopsy, while others suggest that levels greater than 2.5 ng/mL should have a prostate biopsy. However, based on clinical data, it appears that using a PSA cut-off of 4.0 ng/mL for PSA testing will miss a number of potentially curable prostate cancers. Studies have found that 30-35% of men with a PSA value of 2.5 to 4.0 mg/mL will be diagnosed with prostate cancer. For this reason, the NCCN guidelines recommend considering biopsies for men who have PSA levels of 2.5 to 4.0 ng/mL.2
PSA test results can be confusing and do not always mean that cancer is present. Certain other conditions, such as benign prostatic hypertrophy (also called BPH - a type of noncancerous prostate enlargement) and prostatitis (inflammation of the prostate), may also cause an abnormal PSA result.
Additional PSA Tests
Because PSA test results can be confusing, your physician may advise you to consider having one or more of the following PSA tests as described below. These additional PSA tests may help the physician determine the likelihood of the presence of prostate cancer and if a prostate biopsy is needed.
PSA Velocity
PSA velocity is the rate of change in PSA over time. To determine PSA velocity, the NCCN guidelines recommend that multiple PSA values (a minimum of 3) be collected over time intervals of no less than 18 months.2
This rate of change over time provides additional information to your physician in making a determination that prostate cancer may be present.
It is important to remember that men with very high PSA velocity are more likely to have prostatitis (inflammation of the prostate gland) than prostate cancer. Therefore, your doctor will try to rule out prostatitis by further evaluation, which may include antibiotic therapy.2
Age- and Race-Specific PSA Reference Ranges
Another method of PSA testing is age- and race-specific PSA reference ranges. Age- and race-specific PSA reference ranges compare the PSA test results among men in the same group. For example, if a man's PSA levels are high compared to his own age or racial group, there is a greater chance that prostate cancer could be present.
However, since the exact role of age- and race-specific reference ranges in the early detection of prostate cancer remains a continuing source of debate among scientists, the NCCN has chosen not to incorporate these into their current guidelines for the early detection of prostate cancer.2
Percent Free-PSA (fPSA)
There are two forms of PSA in the blood. PSA circulates in the blood in an unbound (or free) form and a form bound to blood proteins. These two together are total PSA.2
Percent-free PSA (fPSA) is the percentage of the total PSA that is unbound. Evidence suggests that fPSA is lower in men who have prostate cancer compared with men who do not.2
NCCN has incorporated fPSA measurement in their guidelines for use in selected circumstances.2 If you want to learn more about fPSA measurement and if it would be right for you, you are encouraged to speak with your doctor.
Complexed PSA (cPSA)
There are two forms of PSA in the blood. PSA circulates in the blood in an unbound (or free) form and a form bound to blood proteins (complexed). These two together are total PSA.2
The complexed PSA (cPSA) test measures the amount of bound PSA circulating in the blood.2
NCCN has incorporated cPSA measurement in their guidelines for use in selected circumstances.2 If you want to learn more about cPSA measurement and if it would be right for you, you are encouraged to speak with your doctor.
PSA Density (PSAD)
PSA density (PSAD) is a test sometimes used by doctors in patients who have a large prostate gland.
To determine PSAD, the PSA value (ng/mL) is divided by the volume (size in cubic centimeters) of the prostate. The size of the prostate gland is determined by transrectal ultrasound (TRUS), a procedure that uses sound waves to create a picture of the prostate.2
The NCCN does not incorporate PSAD into their early detection guidelines due to the lack of widespread acceptance by physicians and because it offers little benefit over PSA velocity, cPSA and fPSA.2
References
- Cancer Facts & Figures 2008. American Cancer Society. http://www.cancer.org. Accessed June 9, 2008.
- NCCN® Clinical Practice Guidelines in Oncology - v.2.2007. Prostate Cancer Early Detection; 2007. National Comprehensive Cancer Network. www.nccn.org. Accessed June 9, 2008.
This information is intended for US consumers only.