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Prostate Cancer Detection

In this Section:

• Digital Rectal Examination and PSA
• Current Screening Recommendations
• Biopsy

 

Digital Rectal Examination and PSA

Prostate biopsy prompted by abnormal findings on digital rectal exam (DRE), such as nodularity or induration of the prostate leads to a diagnosis of prostate cancer in only 15%-25% of cases. This compares with prostate cancer prevalence of less than 5% among men of similar age without abnormal DRE. Although neither accurate nor sensitive for prostate cancer detection, abnormal DRE is associated with a 5-fold increased risk of cancer present at time of screening.

PSA has revolutionized prostate cancer screening. PSA is a serine protease produced by the prostatic epithelium and secreted in the seminal fluid in large quantities. Prostatic disease changes the cellular barriers that normally keep PSA within the ductal system of the prostate and thereby alters serum levels. The level of PSA in serum is increased by inflammation of the prostate, urinary retention, prostatic infection, benign prostatic hyperplasia, prostate cancer, and prostatic manipulation.

Like DRE, PSA is, therefore, neither accurate nor optimally sensitive for prostate cancer screening; only 15%-25% of cases with PSA greater than 4.0 ng/dL are found to have prostate cancer on biopsy.

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Current Screening Recommendations

The American Cancer Society recommends that the PSA test and the DRE should be offered annually beginning at age 50 to men who have a life expectancy of at least 10 years. Men at high risk should begin testing at age 45. Prior to testing, men should have an opportunity to learn about the benefits and limitations of testing for early prostate cancer detection and treatment.

Men who ask the clinician to make the testing decision on their behalf should be tested. A clinical policy of not offering testing, or discouraging testing in men who request early prostate cancer detection tests, is inappropriate.

High-risk groups include men of African descent (specifically, sub-Saharan African descent) and men with a first-degree relative diagnosed at a younger age. Risk increases with the number of first-degree relatives affected by prostate cancer. The ACS recommends that these men begin testing for early prostate cancer detection at age 45. Men at appreciably higher risk of prostate cancer due to multiple first-degree relatives who were diagnosed with prostate cancer at an early age should be informed regarding possible risks and benefits of screening.

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Biopsy

When indicated, prostate biopsy usually is performed as an office procedure by transrectal ultrasound guidance using an automated 18-gauge biopsy gun. The procedure is done without the need for anesthesia and carries a risk of significant infection of only 1 in 200. Some blood in the urine or in bowel movements can be common for 2-3 days following the biopsy. Blood in the semen may last for up to 2-3 weeks.

If the biopsy is negative, these men are typically followed by checking PSA and rectal exam annually. Repeat biopsy may be needed if PSA levels rise at abnormal rates (> 0.8 ng/dL/year) or if rectal exam shows new nodularity or induration. Men in whom high-grade prostatic intraepithelial neoplasia is found on biopsy may undergo repeat biopsy, since about one-third will be found to have prostate cancer.

One caveat to PSA screening is its lack of specificity when the value lies between 4 and 10ng/cc, since many men with benign prostatic hyperplasia have PSA levels in this range. There have been several attempts to increase testing specificity, including the development of age-specific ranges, trends in PSA increase over time (PSA velocity), and calculations of the PSA density based on the volume of the prostate gland. A commonly employed test to increase testing specificity in this 'indeterminate zone' is the percent-free PSA. Currently, biopsy is recommended in men whose percent-free PSA is < 10%, while biopsy is not necessary when percent-free PSA is > 25%.

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See Also:

PSA Screening