March. 4, 2010 -- The American Cancer Society says men should talk to their doctors about the benefits and limitations of prostate cancer screening before deciding whether to be tested.
The American Cancer Society stopped recommending routine PSA screening more than a decade ago, but the new recommendations are unequivocal in calling for all patients to be informed about the benefits and risks of PSA testing before screening takes place.
"There is a lot of uncertainty with prostate cancer screening," American Cancer Society Director for Prostate and Colorectal Cancers Durado Brooks, MD, MPH, tells WebMD. "Right now it is not entirely clear that finding a man's prostate cancer early will save his life."
Two studies reported early last year heightened long-standing concerns that the risks of routine prostate cancer screening may outweigh the benefits.
Benefits and Limits of PSA Tests
A large trial supported by the National Cancer Institute failed to show a reduction in prostate cancer deaths associated with PSA screening over an average of seven years of follow-up.
Another study from Europe found that routine screening reduced the rate of prostate cancer death by 20%.
But researchers also estimated that 1,400 men would have to be screened and close to 50 men whose cancers were detected through screening would have to be treated to prevent a single cancer death.
Fred Hutchinson Cancer Center biostatistician Ruth Etzioni, PhD, who co-wrote the revised American Cancer Society guidelines, says it isn't that simple.
"The risk-benefit ratio for screening is very different for a man in his 50s and a man in his 70s," she says.
According to Etzioni's own research, one in four men whose prostate cancer is detected through PSA screening actually has clinically irrelevant, slow-growing cancer that would never cause symptoms.
And one in four men will die of their cancer, she says.
Before routine screening, she says about 9% of men received a diagnosis of prostate cancer during their lifetimes and about 3% of men died of the disease.
In the screening era, about 18% of men are now diagnosed with prostate cancer and 2% to 2.5% die as a result.
"The death rate has definitely come down, but treatments are now better and other changes have occurred so it is unlikely that this is completely related to screening," Etzioni says.
The risk of being diagnosed with a clinically irrelevant prostate cancer is much greater for older men than for younger ones, she adds.
Impotence, incontinence, and bowel issues are common side effects of prostate cancer treatment.
The PSA Screening Conversation
Brooks says the conversation between a man and his health care provider should focus on his individual risk.
The new guidelines state that:
- The discussion should begin at age 50 for men with an average prostate cancer risk and at age 45 for men at higher risk -- including African-Americans and men with a close relative diagnosed with the disease before age 65. For men at the highest risk, including those with a strong family history of the disease, the discussion should begin at age 40.
- Men who are tested and have an initial PSA of less than 2.5 ng/mL can be retested every two years.
- Yearly screening is warranted for men with PSA levels of 2.5 ng/mL or higher.
- Men without prostate cancer symptoms who are not expected to live for at least 10 years are not likely to benefit from screening and should not be tested.
- A PSA of 4.0 ng/mL or higher remains a "reasonable threshold" for recommending a biopsy.
Growing questions about the value of PSA testing led the nation's largest group of urologists to revise its own prostate cancer screening guidelines last year.
The American Urological Association dropped its recommendation for annual screening for men age 50 and older in favor of a first-time test at age 40, with the schedule of follow-up testing to be determined on an individual basis.
In a news release issued Wednesday, American Urological Association President Anton J. Bueschen, MD, applauded the American Cancer Society for stressing the importance of patient education in making decisions about screening. But he also warned that assigning a cutoff of 4.0 ng/mL for further evaluation will confuse patients.
"When we look at the biopsies of men who had PSA levels of between 2.0 and 4.0 ng/mL, between 15% to 20% of the time we find cancer," Bueschen tells WebMD.
Thomas Kirk, who is president and CEO of the prostate cancer patient support group Us TOO International, tells WebMD that the confusion surrounding PSA screening points to the need for more research to distinguish between very aggressive and indolent tumors.
"For the most part, doctors cannot tell a patient if his cancer will be slow-growing or aggressive," he says.