USPSTF Recommends Against PSA-based Prostate Cancer Screening

Task Force Says Evidence Does Not Support Use

October 12, 2011 05:00 pm David Mitchell

The U.S. Preventive Services Task Force, or USPSTF, has once again rejected the status quo, following the evidence to propose a recommendation some likely will find controversial. (Editor's Note: The public comment period for the draft recommendation ended Nov. 8, and the draft recommendation has been removed from the USPSTF website. When the recommendation is finalized, it will be posted(www.uspreventiveservicestaskforce.org) on the USPSTF site.)

The task force has published draft recommendations against prostate-specific antigen-, or PSA-, based screening for prostate cancer in asymptomatic men. The USPSTF gave the guidance a D recommendation(www.uspreventiveservicestaskforce.org), which means there is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits, and the task force discourages use of the service.

Story highlights

  • The U.S. Preventive Services Task Force, or USPSTF, has issued a draft recommendation against prostate-specific antigen, or PSA, screening for prostate cancer in asymptomatic men because evidence indicates that the harms of the test outweigh its benefits.
  • The AAFP's Commission on Health of the Public and Science is reviewing the recommendation.
  • The public may provide feedback during an open comment period that ends Nov. 8.

The Oct. 7 recommendation was made based on an evidence review(www.uspreventiveservicestaskforce.org) of more than 60 trials and studies that specifically involved PSA-based screening or assessed the harms and benefits of prostate cancer treatment.

"At this point, we have no good evidence that PSA-based prostate cancer screening does any good, though we hold out hope there may be a small benefit," said USPSTF Co-vice Chair Michael LeFevre, M.D., M.S.P.H., who added that roughly 75 percent of U.S. men older than age 50 have had at least one PSA-based screening. "But the harms are at least moderate."

The task force was at the center of a controversy two years ago when it recommended(www.uspreventiveservicestaskforce.org) a shift from annual to biennial screening mammography in women ages 50-74. It also recommended against routine screening mammography for women ages 40-49 who aren't at increased risk for breast cancer, saying women in the latter age group should make a personal decision about screening based on a discussion with their doctor.

Since those recommendations were released, the USPSTF has altered its recommendation process to include a public comment period(www.uspreventiveservicestaskforce.org). The AAFP's Commission on Health of the Public and Science is reviewing the prostate cancer screening recommendation and plans to provide feedback during the comment period, which ends Nov. 8.

"The AAFP has a high regard for the rigorous process used by the USPSTF and rarely disagrees with its analysis and recommendations," said Herbert Young, M.D., director of the AAFP's Health of the Public and Science Division and the staff executive for the commission.

Vitamin E Supplements Increase Prostate Cancer Risk, Study Finds

Daily vitamin E supplementation in men is associated with a statistically greater risk of developing prostate cancer, according to the results of an updated review of data from the long-running Selenium and Vitamin E Cancer Prevention Trial(www.cancer.gov), or SELECT.

Specifically, the review found that 76 prostate cancers occurred in every 1,000 men who took 400 international units of vitamin E each day compared with 65 cancers per 1,000 men who took a daily placebo during a seven-year period. This difference represents a 17 percent increase in prostate cancers among vitamin E users compared with those who took a placebo.

The review(jama.ama-assn.org) appears in the Oct. 12 issue of JAMA: The Journal of the American Medical Association.

SELECT, which began in 2001 and included more than 35,000 men, originally was undertaken to substantiate earlier findings from studies in which prostate cancer risk was not the primary outcome but that suggested a possible role for selenium and/or vitamin E in prostate cancer prevention. The trial was to last a minimum of seven years and a maximum of 12 years.

However, the independent data and safety monitoring committee for the trial that met in 2008 to review initial SELECT study data found that selenium and vitamin E, taken alone or together, did not prevent prostate cancer. The committee also determined that it was unlikely selenium and vitamin E supplementation would ever produce a 25 percent reduction in prostate cancer incidence, as the study was designed to show. Therefore, men in the study were told to stop taking their supplements.

Despite the closing in 2010 of the study's numerous clinical sites, researchers continued to follow consenting study participants to monitor their health status. Now, in light of this latest finding, the researchers are encouraging all participants to consider taking part in long-term study follow-up so investigators can continue to track outcomes.

In 2008, the USPSTF recommended against screening for prostate cancer in men age 75 years or older and concluded that evidence was insufficient to assess the balance of benefits and harms of screening men younger than 75.

LeFevre, who publicly questioned the value of PSA-based screening more than a dozen years ago, told AAFP News Now that more than 300,000 men have been enrolled in randomized screening trials in nine countries and, after 10 years of follow-up, "the hoped-for benefit is not apparent."

LeFevre is professor and assistant chair in the department of family and community medicine at the University of Missouri, Columbia. He said that for every 1,000 men treated for prostate cancer, five die of perioperative complications; 10-70 suffer significant complications but survive; and 200-300 suffer long-term problems, including urinary incontinence, impotence or both.

"That's a lot of harm for a cancer that didn't need to be treated in the first place," he said.

The task force acknowledged in its recommendation that there is convincing evidence that PSA-based screening results in the detection of many cases of asymptomatic prostate cancer.

However, the USPSTF noted, the majority of men who have asymptomatic cancer detected by PSA screening have a tumor that meets histological criteria for prostate cancer, but that tumor either will not progress or is so indolent and slow-growing that it will not affect the men's lifespans or cause adverse health effects because the men are likely to die of other causes first.

"The evidence is convincing that for men aged 70 years and older, screening has no mortality benefit," the task force wrote. "For men aged 50 to 69 years, the evidence is convincing that the reduction in prostate cancer mortality 10 years after screening is small to none. … Ninety-five percent of men with PSA-detected cancer who are followed for 12 years do not die from that cancer, even in the absence of definitive treatment."

LeFevre said the recommendation likely won't stop some physicians from offering screening, and it won't stop some patients for asking for it.

"While the USPSTF discourages screening tests for which the benefit does not outweigh the harms, we certainly understand this test is in wide use," he said. "If an individual man asks me for it, I'll respond with a balanced discussion about what we don't know, which is whether there is there is any benefit, and what we do know, which is that there are significant harms. I'll still order the test if a man who knows the evidence says he still wants it."

In its draft recommendation, the USPSTF called for additional research in a number of areas related to prostate cancer screening, including the need for a comparison of the long-term benefits and harms of immediate treatment versus observation with delayed intervention. The task force said that 90 percent of men with PSA-detected prostate cancer seek treatment, which typically involves surgery or radiotherapy.

The American Urological Association, or AUA, which supports the use of the PSA test, said in an Oct. 7 statement(www.auanet.org) that it is in the process of developing a new clinical guideline for prostate cancer screening. The AUA said its panel will review the use of the PSA test, early detection of prostate cancer, and new tests and diagnostics.


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