Men's Health

Lack of evidence limits comparison of effectiveness of localized prostate cancer treatments

Prostate cancer is being detected earlier than in the past because of the development of the prostate-specific antigen (PSA) assay as a diagnostic test. However, there is little evidence from randomized, clinical trials (RCTs) to indicate which treatments are most effective or produce the fewest harmful effects in patients with clinically localized disease, especially when detected early using PSA, finds a new study. Although there are a variety of treatments for localized prostate cancer—including surgery, androgen deprivation therapy (to reduce male hormones), and localized radiation therapy—the lack of information from high-quality randomized trials presents a barrier to well-informed decisionmaking by patients and clinicians.

Timothy J. Wilt, M.D., M.P.H., and colleagues at the Minnesota Evidence-based Practice Center conducted a systematic review of relevant RCTs and observational studies on the treatment of localized prostate cancer. The researchers found that no treatment option had consistent results from at least two high-quality RCTs, which had adequate followup and sufficient patients enrolled to find significant differences in outcomes. In addition, none of the RCTs compared standard therapies with emerging therapies.

Two RCTs compared radical prostatectomy (surgical removal of the prostate) with watchful waiting. A study of 695 men found that surgery (compared with watchful waiting) significantly reduced the risk of death from prostate cancer at 10 years from 15 percent to 10 percent, and the risk of metastases (spread to other organs) at 10 years from 25.4 percent to 15.2 percent. However, very few of the men in this trial had cancer that was detected by PSA testing. Other studies compared variations on surgery (with or without androgen deprivation) or radiation therapy (external-beam radiation therapy or EBRT with or without androgen deprivation), brachytherapy (implanted pellets of radioactive material, with or without EBRT), or other combinations. A number of clinical trials are underway that may help fill in the gaps in knowledge of the comparative effectiveness of and risk of harms associated with various prostate cancer treatments.

The study was funded by the Agency for Healthcare Research and Quality (Contract No. 290-02-0009) as a part of the Agency's Effective Health Care Program. For more information, go to http://effectivehealthcare.ahrq.gov.

See "Systematic review: Comparative effectiveness and harms of treatments for clinically localized prostate cancer," by Dr. Wilt, Roderick MacDonald, M.S., Indulis Rutks, B.A., Tatyana A. Shamliyan, M.D., M.S., and others in the March 18, 2008, Annals of Internal Medicine 148(6), pp. 435-448.

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