The conflicting study results and guidelines have left clinicians and patients without a clear message on prostate screening recommendations. Prostate cancer will be diagnosed in almost 200,000 US men in 2009, but the PSA test does not distinguish between a localized, very slow-growing cancer or an aggressive, potentially fatal malignancy.5 Most diagnosed prostate cancers are clinically localized, and most will never cause symptoms or death. Autopsy reports have found prostate cancer present in up to 70% of men in their 60s and up to 83% of men in their 70s. But a man's lifetime risk of dying from prostate cancer is 3% to 4%.5
A positive PSA test result usually triggers a cascade of events that may include biopsy, surgery, hormone therapy, and radiation or brachytherapy, as well as the risk of urinary incontinence, erectile dysfunction, and bowel dysfunction. Most men with localized cancer opt for treatment, whereas only 10% choose active surveillance or watchful waiting.5
The ERSPC trial cited the known adverse effects of prostate cancer screening—high rates of overdiagnosis and overtreatment in men whose cancer would never have caused clinical symptoms.2 Otis Brawley, MD, chief medical officer of the American Cancer Society, interpreted the ERSPC results as “if you choose to be screened, it means you are 48 times more likely to be treated, and face all the problems associated with treatment, than you are to avoid death.”6
Both the ERSPC and the PLCO studies have significant limitations, including a short follow-up time, that are well-debated in the literature.7 These studies are still ongoing and are expected to yield valuable data with more years of follow-up.
After the publication of the preliminary results of these two studies, the balance of benefits and harms of prostate cancer screening is still unknown.7 There are several tests that attempt to improve the accuracy of routine PSA screening by evaluating PSA velocity, PSA density, PSA slope, and determination of free-to-total serum PSA. There is, however, no evidence of improved mortality outcomes using these markers.5
Efforts are under way to find more useful biomarkers that will distinguish between indolent and aggressive tumors, and risk-assessment tools are being developed to identify men at highest risk for potentially lethal cancers.5 Prevention of prostate cancer through vitamin E and selenium supplementation has been disproved in a large trial, but multiple studies have demonstrated that finasteride (Proscar, Propecia, generics), which is widely prescribed for benign prostatic hypertrophy, has been shown to reduce the risk of prostate cancer.6
All the guidelines recommend that clinicians and patients engage in shared decision making around the topic of prostate cancer screening (Table 2). Informing patients of the risks and benefits of prostate cancer screening is essential, but it is also time-consuming. The CDC has published an easy-to-read booklet, Prostate Cancer Screening: A Decision Guide, available at www.cdc.gov/cancer/prostate/basic_info/screening.htm. There are similar booklets posted for African-American men and Spanish-speaking men. These resources are intended to assist clinicians and patients in discussions leading to informed decision making regarding PSA testing. JAAPA
Timothy Quigley is associate professor in the PA program at the College of Health Professions, Wichita State University, Wichita, Kansas. He has indicated no relationships to disclose relating to the content of this article.
Sarah Zarbock, PA-C, department editor
REFERENCES
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2. Schröder FH, Hugosson J, Roobol MJ, et al; ERSPC Investigators. Screening and prostate-cancer mortality in a randomized European study. N Engl J Med. 2009;360(13):1320-1328.
3. American Urological Association. Prostate-Specific Antigen Best Practice Statement: 2009 Update. http://www.auanet.org/content/guidelines-and-quality-care/clinica-guidelines/mainreports/psa09.pdf. 2009. Accessed September 2, 2009.
4. US Preventive Services Task Force. Screening for prostate cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149(3):185-191.
5. Brawley OW, Ankerst DP, Thompson IM. Screening for prostate cancer. CA Cancer J Clin. 2009;59(4):264-273.
6. Mitka M. Guideline supports long-term use of medication to lower prostate cancer risk. JAMA. 2009;301(17):1753-1754.
7. Barry MJ. Screening for prostate cancer—the controversy that refuses to die. N Engl J Med. 2009;360(13):1351-1354.