SAN FRANCISCO -- Older men with limited life expectancies are getting screened much too often for prostate cancer, given the potential harm that may follow a positive test versus the likelihood of benefit, researchers here reported.
SAN FRANCISCO, Nov. 14 -- Older men with limited life expectancies are getting screened much too often for prostate cancer, given the potential harm that may follow a positive test versus the likelihood of benefit, researchers here reported.
In a cohort study of 597,642 U.S. veterans, 70 and older, many non-clinical factors, such as marital status and region of the country, had a greater effect on prostate-specific antigen (PSA) screening than health, according to a report in the Nov. 15 issue of the Journal of the American Medical Association.
More than half of these men (median age 77), with no previous history of prostate cancer or elevated PSA, had a PSA test, found Louise Walter, M.D., of the San Francisco VA Medical Center and the University of California San Francisco, and colleagues.
Among men older than 85, PSA rates for those in good health were similar to those in poor health, the investigators reported.
Most screening guidelines-the American Cancer Society and the American Urological Association, for example--do not recommend PSA screening in elderly men with limited life expectancies, less than 10 years, Dr. Walter said.
The potential harm from post-screening treatment (biopsy, surgery, incontinence, bowel dysfunction, impotence) occurs immediately and outweighs potential benefits that might not occur until several years in the future, she said.
Because, the researchers noted, there are no large-scale studies of actual PSA screening practices in elderly men according to life expectancy, they undertook a PSA screening study using VA databases and linked Medicare claims.
The men, with no history of prostate cancer or elevated PSA, were seen at 104 U.S. Veterans Affairs facilities during 2002 and 2003.
Charlson comorbidity scores were used to stratify the men into three groups, ranging from best health (score=0) to worst health (score=4 or greater). Thirty percent of the men had a Charlson score of 0, while 15% had a score of four or more.
In 2003, 56% of the elderly men had a PSA test. Although PSA screening rates decreased with advancing age, within each five -year age group the percentage of men who underwent a PSA test did not substantially decline with worsening health, the researchers reported.
For example, among men ages 85 years and older, 34% in best health had a PSA test compared with 36% in worst health. Of the men in worst health, 68% had diabetes and 47% had congestive heart failure.
The percentage of men who had a PSA test in 2003 decreased with advancing age from 64% for men age 70 to 74 to 36% for men 85 years or older (P<.001).
Yet less than 10% of the men in this age group are expected to survive 10 years, the researchers said. Furthermore, the screening rates did not decrease as much as estimated 10-year survival rates decreased with advancing age.
There is strong evidence, the researchers said, that few men 70 years or older with a Charlson score of four or more will survive 10 years, yet 51% had a PSA test in 2003, representing 46,000 veterans.
In multivariate analyses, the effect of health status on PSA screening remained small even after adjustment for all factors. In addition, non-clinical factors, such as marital status, region of the country, or living in higher income areas, continued to be more predictive of PSA screening than health.
Even among men with the highest PSA screening rates, worsening health was associated with only a small decrease in screening rates. For some subgroups of men in worst health, screening rates exceeded 60%, the investigators reported.
Some of the explanations for these findings included the following possibilities:
The study had several limitations, the researchers said. Laboratory and claims data did not give reasons why a test was ordered, although the chart reviews suggested that this in cohort, PSA tests were ordered for screening purposes.
Also, screening usage may have been underestimated because Medicare claims do not capture PSA tests paid for by other sources.
While the Charlson index is strongly predictive of mortality, the researchers noted that it does not include all factors that may determine life expectancy, such as physical functioning or lab values. Better tools are needed, they said.
Finally, they said, generalizability to men who do not use the VA system is uncertain, although the VA itself is the largest health care system for men in the U.S.
In conclusion, the researchers wrote that PSA screening rates among elderly veterans with limited life expectancies should be much lower than current practice. Guidelines should be more explicit about how life expectancy is defined and provide tools to help clinicians identify men who have poor prognoses, considering both advancing age and the presence of severe comorbidities.
These men, Dr. Walter's team suggested, should be told that PSA screening is more likely to harm than help them. Prior studies have shown that educating men about PSA screening reduced patient interest in screening and led to fewer PSA tests. This in turn would allow efforts to be directed toward prevention strategies in elderly men that have more immediate benefits and better evidence of effectiveness.
In an editorial in the same JAMA issue, Peter Albertsen, M.D., of the University of Connecticut Health Center in Farmington, wrote that even under favorable assumptions, routine PSA screening is unlikely to benefit most men who have a low probability of surviving 10 years. Nevertheless, most men are overly optimistic about their own longevity so that these statistics are meaningless. Patients make decisions on the basis of their own personal fears, and being diagnosed with cancer is one of them, he said.
So how does a simple blood test cause harm? Dr. Albertsen asked. Most of the morbidity associated with PSA testing, he said, is related to the procedures that follow a prostate cancer diagnosis. For example, in the Prostate Cancer Outcomes Study, of the 1,291 men undergoing a radical prostatectomy, 59.9% were impotent, and 8.4% were incontinent within 18 months of surgery. Of 497 patients treated with external beam radiation, 43% of previously potent men were impotent within two years, and 5.4% had significant bowel dysfunction.
Furthermore, Dr. Albertsen said, repeated testing for PSA has increased the rate of prostate biopsy and has raised the probability of detecting indolent rather than life-threatening disease.
Two large randomized ongoing studies designed to test the benefit of PSA screening in all men have yet failed to demonstrate a clinically significant advantage for men in the screening group, he said. Natural history suggests that young men, ages 50 to 70, are most likely to benefit from screening. Applied to older men, the benefits are not likely to exceed the potential harm, he said.
Although public health policy does not support PSA screening for elderly men, physicians order the tests anyway because of patients' exaggerated fears and overestimation of treatment efficacy, Dr. Albertsen said.
Physicians also order the tests, he wrote, because the reward for treatment can be significant and the penalty for failing to diagnose can be severe. "This dilemma is quite common in the current health care system and certainly requires urgent attention in the near future," Dr. Albertsen concluded.