PSA: To Screen or Not to Screen

Screening for prostate cancer does work, despite controversy about its efficacy, according to IPCC Co-chair Leonard G. Gomella, who opened the congress with a discussion of the current status of prostate cancer screening.

“There is no consensus or uniformly accepted guidelines” on screening for prostate cancer, said Gomella, a professor and chairman of the Department of Urology, and associate director of clinical affairs at the Jefferson Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA. Gomella added that this lack of consensus leads to mixed messages among physicians and patients.

The primary authorities in the United States on prostate screening—the US Preventive Services Task Force (USPSTF), the National Comprehensive Cancer Network, the American Cancer Society (ACS), and the American Urological Association—each offer its own recommendations. For example, the USPSTF recommends not screening men >75 years of age, and the ACS does not recommend routine screening and says the digital rectal examination (DRE) is optional.

The groups do agree in some areas, such as a trend toward earlier screening. Three of the 4 groups (the USPSTF does not) now recommend screening high-risk men starting at age 40. Contributing factors include the value of baseline prostate-specific antigen (PSA) at age 40 as an indicator of future risk and the reduced impact of benign prostatic hyperplasia (BPH) on PSA in younger men.

The primary concern among all of these groups remains overdiagnosis and overtreatment. For these reasons, screening has become “more of a discussion between the provider and the patient,” Gomella said. The physician will present the benefits and risks and then arrive at a consensus with the patient on whether or not to screen.

The Value of PSA Testing

Much of the controversy over prostate screening centers on the efficacy of the PSA test. Since widespread PSA-based screening began in the US, death rates from prostate cancer have declined approximately 4% per year, according to Gomella. The PSA test has led to earlier diagnosis of prostate cancer and detection of more localized disease. However, Gomella added, “while PSA is great, it’s not perfect.”

Conditions such as prostatitis or BPH can elevate PSA levels and lead to false positives. Other factors, such as medications, can lower PSA levels and result in prostate cancer being undetected. PSA test standards are not uniform, so a patient’s score is sometimes inconsistent between laboratories. Additionally, a study by Thompson et al found that there is no PSA level below which a physician can definitively say a patient does not have prostate cancer (N Engl J Med. 2004;350:2239-2246).

Still, Gomella is an advocate of the PSA. “It does give us some insight into who we should follow a little more closely and screen more frequently, and which patients we can back off a little bit because they have a relatively low lifetime risk,” he said.