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Cancer Screening in Older Patients: Making Decisions About Age Cutoffs

Karen Young Kreeger

Age cutoffs for cancer screening vary from cancer to cancer. The latest U.S. Preventive Services Task Force recommendation for mammograms states that "there is insufficient evidence to recommend for or against routine mammography for women aged 40–49 or aged 70 and older . . . although [a] recommendation for healthy women aged 70 and older may be made on other grounds."

For Pap smears, the USPSTF recommends regular testing, but notes that there is "insufficient evidence to recommend for or against an upper age limit for Pap testing, but recommendations can be made on other grounds to discontinue regular testing after age 65 in women who have had regular previous screenings in which the smears have been consistently normal." The group suggests screening for colorectal cancer for all persons over 50, with no age cutoff mentioned.

A recent study by a University of California at San Francisco group outlined a conceptual framework for a decision-making tool that could help elderly people decide whether to undergo screening for certain types of cancer.

"I found that when I was in my clinic I was constantly having to make the decision: Should I recommend this particular cancer screening [test] for this person?" said Louise C. Walter, M.D., an assistant professor of medicine at UCSF and a geriatrician at the San Francisco Veterans Affairs Medical Center.



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Dr. Louise C. Walter

 
To Walter and others, cancer screening has become almost automatic, like giving vaccinations to children. "But for cancer screening, I think the risk-benefit ratio as you get older is very close and that’s where [patient] preferences and thought should go into these decisions."

The decision-making tool, developed by Walter and UCSF colleague Kenneth E. Covinsky, M.D., starts by assessing a patient’s risk of dying of cancer according to his or her estimated life expectancy and cancer-specific mortality rates.

The next step considers the likelihood of benefiting from the screening, given a person’s estimated risk of dying of cancer and the efficacy of a certain test. For example, people with less than a 5-year life expectancy are unlikely to benefit from cancer screening. The research was published in the June 6 issue of the Journal of the American Medical Association. The researchers concentrated on mammograms for breast cancer, Pap smears for cervical cancer, and fecal occult blood tests for colorectal cancer.

The framework also considers the possibilities that the screening could be harmful. "The majority of people you screen are not going to have cancer, so you’re subjecting everyone to potential harm from a false positive, or anxiety, or finding something that would have never affected them," said Walter. They also suggest that the patient’s values and preferences about screening should be evaluated.

Walter and Covinsky’s fellow UCSF faculty member Karla Kerlikowske, M.D., associate professor of medicine and of epidemiology and biostatistics, noted that their framework is really based on physiological age, which is hard to determine.

"One thing you can’t get away from is that [after] age 65 the risk of coronary artery disease goes way up, much more than, say, [the risk of] breast cancer, so this makes it hard to benefit from any kind of [cancer] screening," she said. "The probability of dying from any kind of cancer is dwarfed by coronary disease."

Andrew Wolf, M.D., associate professor of medicine at the University of Virginia School of Medicine in Charlottesville, said age may not be the most important factor. "We should really be focusing on prognosis and values. Age is only relevant as a marker for prognosis," he said.



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Dr. Andrew Wolf

 
Importance of Age Cutoffs

These types of tools draw attention to the uncertainty that exists about screening in the growing elderly population.

"I actually don’t think there should be age cutoffs," said Walter. "Certainly age is associated with lower life expectancy, but there’s such great variation that you have to look beyond it. If someone has advanced dementia, that’s what defines their life expectancy."

In 1999, Kerlikowske and her colleagues examined the impact on life expectancy and cost-effectiveness of continuing mammograms in women aged 70 to 79 and found the gains to be small. They came to the conclusion that women’s preferences for a small gain in life expectancy weighed against the potential harms of routine mammograms should play a role in the patients’ decision to continue screening into their 70s and 80s.

‘Downplay the Downsides’

"The prevailing medical culture has tended to downplay the downsides of screening," wrote H. Gilbert Welch, M.D., codirector of the VA Outcomes Group in White River Junction, Vt., and professor of medicine at the Dartmouth Medical School in Hanover, N.H., in an editorial about Walter and Covinsky’s research. Downsides include ambiguous results and the resultant cascade of tests, or unnecessary treatment because of the detection of diseases that are not life threatening.

In the end, said Wolf, age cutoffs in cancer screening guidelines are only as important as the evidence suggests. For some cancers, he noted that there is good data based on age, for example, colorectal cancers, and for other cancers we have no data at all. "We can’t generalize about all screenable cancers. You do have to look at the individual cancer and the individual patient."

The one downside to decision-making tools like that of Walter and Covinsky is that it takes time to discuss these issues with patients. This is where decision-making aids like pamphlets and videos can help to supplement the discussion.

Improving Knowledge

Annette O’Connor, Ph.D., professor of nursing and epidemiology at the University of Ottawa, Ottawa Health Research Institute, said cancer-screening decision aids can improve patients’ knowledge of options, benefits, and harm. She added that they also provide a more realistic modulation of patients’ perceptions of risks and benefit because they use probabilistic numbers, they can enhance participation in decision-making, and they can reduce patients’ inner conflict about making a decision.



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Dr. Annette O’Connor

 
Integrating the science of probabilities and patient values is why cancer screening for elderly patients is such a challenging area, said Wolf. "This population is burgeoning and we have to be equipped to deal with it. . . . We have to move this communication into the public venue so patients can come in having contemplated these issues."

In the end, said Welch, "We have an ethical obligation to invite people to participate in their medical care to make sure that they’re fully informed."



             
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