In a large U.S. cancer database, 14% of prostate cancer diagnoses occurred among men with a prostate-specific antigen (PSA) level of 4.0 ng/mL or lower. More than half of these men had cancer that was considered “low-risk,” but roughly three-quarters were treated aggressively with radical prostatectomy or radiation therapy. These results were published in the Archives of Internal Medicine.

In 2010, an estimated 217,000 U.S. men will be diagnosed with prostate cancer and 32,000 will die of the disease.[1]

Men 50 years of age or older are often offered prostate-specific antigen (PSA) testing for the early detection of prostate cancer. The test may be offered at a younger age to men at high risk of prostate cancer. The PSA test measures proteins that are produced and shed by the prostate. PSA levels tend to be elevated when prostate cancer is present, but levels can also be elevated in benign (non-cancerous) conditions affecting the prostate.

For men with elevated PSA levels (often defined as a PSA level higher than 4.0 ng/mL), a prostate biopsy may be recommended in order to determine whether or not prostate cancer is present. Prostate cancer can also be present among men with lower PSA levels, however, which has led some researchers to suggest lowering the threshold for biopsy in order to detect more cancers.

A potential concern with lowering the threshold for biopsy is that it could increase the overdiagnosis and overtreatment of prostate cancer. Many prostate cancers will never cause health problems during a man’s lifetime. Treatment of these indolent cancers exposes men to the risk of treatment side effects without providing a health benefit; this constitutes “overtreatment.” Unfortunately, although some prostate cancers can be classified as “low-risk” on the basis of tumor stage, PSA level, and Gleason score, it is still not possible to know for certain which prostate cancers require treatment and which don’t.

To explore the characteristics and treatment of prostate cancers among men with low PSA levels, researchers evaluated information from a large U.S. cancer database: the Surveillance, Epidemiology, and End Results (SEER) system.[2] Information was available for almost 124,000 men diagnosed with prostate cancer between 2004 and 2006.

• 14% of the prostate cancer diagnoses occurred among men with a PSA level of 4.0 ng/mL or lower.
• 54% of the prostate cancer cases among men with low PSA levels were considered “low-risk” on the basis of tumor stage, PSA level, and Gleason score. By comparison, among men with PSA levels between 4.1 and 10.0 ng/mL, 48% of prostate cancers were considered low risk.
• 77% of prostate cancer patients with low PSA levels were treated aggressively with either radical prostatectomy or radiation therapy. This is similar to the rate of treatment among men with higher PSA levels.

The researchers conclude: “Most men diagnosed as having prostate cancer with a PSA threshold below 4.0 ng/mL had low risk disease but underwent aggressive local therapy. Lowering the biopsy threshold but retaining our inability to distinguish indolent from aggressive cancers might increase the risk of overdiagnosis and overtreatment.”

References:

[1] American Cancer Society. Cancer Facts & Figures 2010. Accessed July 27, 2010.

[2] Shao Y-H, Albertsen PC, Roberts CB et al. Risk profiles and treatment patterns among men diagnosed as having prostate cancer and a prostate-specific antigen level below 4.0 ng/mL. Archives of Internal Medicine. 2010;170:1256-1261