By Nancy Walsh, Staff Writer, MedPage Today
Published: November 25, 2011
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
The time has come for a fundamental shift in attitude toward cancer screening, with greater emphasis on providing the public with information about absolute risks and the potential for harm associated with screening, according to a behavioral oncology researcher.
The firestorm that erupted after the U.S. Preventive Services Task Force recommended against mammograms for women ages 40 to 49 was emblematic of the controversies generated among healthcare providers, the public, and advocacy groups every time new guidelines are announced, according to Michael Edward Stefanek, PhD, of Indiana University in Bloomington.
A perspective that is unappreciated is that at least 1,900 women in their 40s would need to undergo mammography to avoid one death over 11 years. During that follow-up time, there would be 2,000 false-positive tests, "along with the resulting unnecessary biopsies, overdiagnosis, and overtreatment," Stefanek explained in a commentary in the December 20 issue of the Journal of the National Cancer Institute.
Even routine mammography for women ages 50 to 70 -- a recommendation that has not been seen as controversial -- has considerable opportunity for harm, with 838 women having to be screened during six years to prevent a single death from breast cancer.
And among women in their 50s, five in 1,000 can be expected to succumb to breast cancer during a ten-year period, but annual screening during that time would only prevent one of those five deaths. Nearly 1,000 women "screened for ten years will have gained nothing, and may have been subject to as many as 50% false-positive tests, unnecessary biopsies, overdiagnosis, and overtreatment for breast cancer," he argued.
The public has not been well served by policy makers and institutions that have taken the approach of emphasizing the benefits of cancer screening, particularly in reducing mortality, and downplaying the consequences, particularly of unnecessary treatments, he stated.
"There will come a time when all the patients have been followed, all the analyses done, all the groups assembled, and all the editorials written, and we still will not be secure in our knowledge of the individual harms and benefits of cancer screening. It appears that this time has come," wrote Stefanek, who has previously held positions at the National Cancer Institute and the American Cancer Society.
The evidence for prostate cancer screening also is ambiguous. For instance, one study that included 20,000 men who had prostate-specific antigen (PSA) testing every two years or no screening found a decrease in deaths from prostate cancer of nearly 50% with the test over 14 years.
Yet a meta-analysis that included almost 400,000 men found no improvement in either overall mortality or prostate cancer-specific deaths.
Moreover, a randomized trial determined that 1,410 men would have to undergo screening and 48 cancers treated to prevent a single prostate cancer-related death, according to Stefanek.
And for the more recent notion of screening smokers for lung cancer using CT scans, the potential harms associated with screening have been clearly demonstrated by the finding that about 95% of positive screens were, in fact, false positives.
To address these concerns, Stefanek offered a number of possible strategies.
An important shift must emphasize the education of healthcare providers and the public, rather than encouraging a specific approach or behavior.
Patients and the public should be given clear information -- based on science rather than opinion or advocacy -- that explains cancer incidence and mortality, and provides transparent information about the risks and benefits of screening.
Furthermore, risks should be presented as absolute rates and in ways that can be easily understood, the researcher advised.
Another component of the new strategy would be the creation of a partnership among scientific and advocacy groups, but not to further develop and disseminate guidelines.
Rather, the task should be to develop the clearest educational materials so patients and caregivers can together make the most appropriate individual decisions on screening.
This informed decision-making approach should be accompanied by the implementation of measures that evaluate the number of patients who have been educated, rather than how many are screened.
In addition to these strategies, "and critically important, we need to energize work to identify markers that discriminate minimal-risk disease likely to have little impact on mortality versus high-risk disease," he wrote.
Shifting screening decisions away from a public health perspective to an informed individual approach will allow consideration of factors typically overlooked, such as anxiety about illness, acceptable degrees of risk, and the negative consequences of unnecessary treatment.
Such an approach, clearly informing patients about both benefits and harms of screening "involves a fundamental respect for individuals and a tolerance for truly informed decisions even if, as individuals ourselves, we would not make the same choice," Stefanek concluded.
Published: November 28, 2011