PSA Testing

PSA Testing: More Harm Than Good?

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The U.S. Preventive Services Task Force (USPSTF) has released a draft document recommending against prostate-specific antigen (PSA)-based screening for prostate cancer.[1] This recommendation applies to asymptomatic men, regardless of age, race, or family history. The Task Force did not evaluate the use of the PSA test as part of a diagnostic strategy in men with symptoms that are highly suspicious for prostate cancer. This recommendation also does not consider the use of the PSA test for surveillance after diagnosis and/or treatment of prostate cancer.

This publication is likely to generate considerable controversy among primary care providers, specialists, and patients because routine PSA screening for men older than 50 years is now the current care. As well, recommendations from the USPSTF are routinely considered in coverage decisions made by insurance companies and other payors.

To put the issue in context, consider this[2]:

If 100 men older than age 50 years are tested, 17 will have prostate cancer.

    • 14 of the men will have a slow-growing prostate cancer and 3 will die of the disease
    • If the 14 men are treated, they could become impotent or incontinent or die
    • About 1 in 500 men who undergoes radical surgery will die from complications of the surgery

The panel cites evidence that PSA-based screening programs result in the detection of many cases of asymptomatic prostate cancer. Although the majority of the tumors may meet histological criteria for prostate cancer, the tumor is likely to grow too slowly to affect a man’s lifespan or cause adverse health effects, because he will probably die of another cause first. The rate of overdiagnosis increases as the number of men subjected to biopsy increases and will also depend on the age at which diagnosis is made. Cancer diagnosis in older men with shorter life expectancies is much more likely to be the result of overdiagnosis.

This recommendation replaces the 2008 recommendation.[2] Whereas the USPSTF previously recommended against PSA-based screening for prostate cancer in men aged 75 years and older and concluded that the evidence was insufficient to make a recommendation in younger men, the USPSTF now recommends against PSA-based screening for prostate cancer in all age groups.

The American Urological Association recommends that PSA screening should be offered to men aged 40 years or older.[3] The American Cancer Society emphasizes informed decision making for prostate cancer: men at average risk should receive information beginning at age 50 years, while African American men or men with a family history of prostate cancer should receive information at age 45 years.[4] The American College of Physicians[5] and the American College of Preventive Medicine[6] recommend that clinicians discuss the potential benefits and harms of PSA screening with men 50 years and older, consider their patients’ preferences, and individualize screening decisions.

This is a draft document only and will be subject to change following public comment, which started October 11, 2011.

Benefits of Detection and Early Intervention

The Task Force chose death from prostate cancer or overall mortality as its primary outcome measure. Based on the available evidence, the panel believes that screening has no mortality benefit for men older than 70 years; for men ages 50 through 69 years, the evidence is convincing that the reduction in prostate cancer mortality 10 years after screening is small to none. No prostate cancer screening study, individually or combined with other screening studies, or study of treatment of screen-detected cancer, has demonstrated a reduction in all-cause mortality.[1,7]

Harms of Detection and Early Intervention

PSA-based screening for prostate cancer results in the diagnosis and treatment of many more cancer cases than would occur without screening; thus, screening results in many more men who are subject to treatment-related adverse events. A sizable proportion of the additional cancer cases that are detected with screening represent overdiagnosis; these men are then subject to all of the related risks of surgery, radiation, or hormone therapy. Even for those men whose screen-detected cancer would otherwise have been later identified symptomatically, a high proportion experience the same outcome, and are thus subjected to the harms of treatment for a much longer period of time.[8] Based on this evidence, the USPTSF believes that PSA-based screening for prostate cancer results in considerable overtreatment.

USPSTF Assessment

The USPSTF concludes that there is moderate certainty that the harms of PSA-based screening for prostate cancer outweigh the benefits.

According to the committee, the common perception that PSA-based early detection of prostate cancer prolongs lives is not supported by the scientific evidence. Results from the two largest clinical trials have been unable to quantify the precise effect of screening and demonstrate that if any benefit does exist, it is very small after 10 years.[7,8] A meta-analysis of all published trials found no statistically significant reduction in prostate cancer deaths.[9] At the same time, overdiagnosis and overtreatment of prostatic tumors that will not progress to cause illness or death are frequent consequences of PSA-based screening. About 90% of men are currently treated for PSA-detected prostate cancer in the United States—usually with surgery or radiotherapy. However, the vast majority of them will be subjected to significant harm without seeing any benefit in cancer prevention or improvement.

This recommendation applies to men in the general U.S. population. Older age is the strongest risk factor for development of prostate cancer. However, a more favorable balance of benefits and harms for PSA-based screening does not accompany this increase in risk. Across age ranges, African American men and men with a family history of prostate cancer have an increased risk for developing and dying from prostate cancer compared with other men. However, the observed risk differences for race/ethnicity or family history are each relatively small when compared with the risk differences seen with increasing age,[2] and there are no data that suggest that the net benefit of PSA-based screening is altered by race or family history.

Recommendations of Others

Prostate cancer is the most commonly diagnosed non-skin cancer in men in the United States, with a lifetime risk of diagnosis currently estimated at 15.9%.[2] Most cases of prostate cancer have a good prognosis, but some are aggressive; the lifetime risk of dying from prostate cancer is 2.8%. Prostate cancer is rare before age 50 years and very few men die of prostate cancer before age 60. The majority of deaths due to prostate cancer occur after age 75 years.[10]

The USPSTF is sponsored by the Agency for Healthcare Research and Quality (AHRQ) and is the leading independent panel of private-sector experts in prevention and primary care. The USPSTF conducts rigorous, impartial assessments of the scientific evidence for the effectiveness of a broad range of clinical preventive services, including screening, counseling, and preventive medications. Its recommendations are considered the “gold standard” for clinical preventive services.

RESOURCE:
ARHQ has published a video to help you discuss “risk versus benefit” of prostate screening with your patients.

Jill Shuman, MS, ELS
Published October 12, 2011
References

  1. Chou R, Croswell JM, Dana T, et al. Screening for prostate cancer: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2011 Oct 7. [Epub ahead of print]
  2. U.S. Preventive Services Task Force. Screening for prostate cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149(3):185-191.
  3. Carroll P, Albertsen PC, Greene K, et al. Prostate-Specific Antigen Best Practice Statement: 2009 Update. Linthicum, MD: American Urological Association Education and Research, Inc; 2009.
  4. Wolf AM, Wender RC, Etzioni RB, et al. American Cancer Society guideline for the early detection of prostate cancer: update 2010. CA Cancer J Clin. 2010;60(2):70-98.
  5. Screening for prostate cancer. American College of Physicians. Ann Intern Med. 1997;126(6):480-484.
  6. Lim LS, Sherin K; ACPM Prevention Practice Committee. Screening for prostate cancer in U.S. men: ACPM position statement on preventive Practice. Am J Prev Med. 2008;34(2):164-170.
  7. Lin K, Croswell JM, Koenig H, et al. Prostate-Specific Antigen-Based Screening for Prostate Cancer: An Evidence Update for the U.S. Preventive Services Task Force. Evidence Synthesis No. 90. AHRQ Publication No. 12-05160-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2011.
  8. Wilt TJ. The VA/NCI/AHRQ Cooperative Studies Program #407: Prostate cancer Intervention Versus Observation Trial (PIVOT): main results from a randomized trial comparing radical prostatectomy to watchful waiting in men with clinically localized prostate cancer. Paper presented at: 107th Annual Meeting of the American Urological Association; May 2011; Washington, DC.
  9. Ilic D, O’Connor D, Green S, Wilt TJ. Screening for prostate cancer: an updated Cochrane systematic review. BJU Int. 2011;107(6):882-891.
  10. Howlader N, Noone AM, Krapcho M, et al. SEER Cancer Statistics Review, 1975–2008. Bethesda, MD: National Cancer Institute; 2011.