"Cancer screening is important in younger and middle-aged populations because early detection can result in the reduction of long-term health risk," said Truls Ostbye, M.D., lead author on the paper that appears in the November/December 2003 issue of the Annals of Family Medicine. "However, in an older population, while the rates of some cancers increase, the risk of dying from a competing disease increases as well, and overall, this reduces the number of years that can be saved through screening." Ostbye is a professor in the department of community and family medicine at Duke.
Although the use of mammography and Pap smears is lower among older women than middle-aged women, the Duke researchers cite data from two large population studies that show screening is on the rise in this age group.
Researchers examined data from the Health and Retirement Study (HRS) and its companion study, The Asset and Health Dynamics Among the Oldest Old (AHEAD), both of which collected data from 1993 to 2000 on how retirement impacts the health and wealth of both men and women. The studies were funded by the National Institute on Aging. In the HRS study, 5,942 women aged 50 to 61 were interviewed about their health behaviors, disease and disability, and medical care usage. The AHEAD study, which collected similar data, focused on 4,543 women aged 70 years and older.
The data showed that almost 70 percent to 80 percent of women aged 50 to 64 had received mammograms in the last two years, and approximately 75 percent of those same women had received Pap smears during that same time interval. In women 85 to 90 years of age, the percentage of women receiving mammograms drops to 40 percent and Pap smears drops to 25 percent. However, for both mammography and Pap smears, rates increased in all groups from 1995/1996 to 2000, including the older age brackets.
Ostbye said that the socioeconomic impact of over-screening is large and not to be ignored, particularly as the U.S. society ages. The researchers estimate that in 2000, 4.6 million women over the age of 70 had mammograms, costing approximately $460 million, and 3.7 million had Pap smears, costing $47 million. These costs do not include subsequent follow-up costs for further evaluation and clinical management.
"Some models suggest that 240 very healthy 80-year-old women would need to be screened with mammography to prevent one death from breast cancer," said Ostbye. "The argument is even stronger regarding Pap smears. Low rates of mortality from cervical cancer are found in the elderly, but physicians continue to screen this group even though there is no scientific evidence suggesting it is beneficial."
The HRS and AHEAD data also point to another problem of screening that is not limited to the elderly: the healthiest people with the lowest risk of disease are those most often screened. For example, nonsmokers and people who perceived their health as excellent, very good or good were the most likely to be screened. Less likely to be screened were people who smoke, are less physically active or deem their health to be poor or fair.
"People who need screening the most are the least likely to get it," said Ostbye. "By examining screening behaviors, we can try and adjust recommendations in low-risk populations and increase incentives in high-risk populations to possibly use our health care dollars more wisely and deliver better health care to all populations."
Ostbye says that part of the problem is that clinical guidelines for the elderly are often ambiguous and research including this age group is almost non-existent. For example, the American Cancer Society (ACS) recommends no specific age for cessation of mammography. ACS recommendations are clearer on Pap smears, citing that women aged 70 and older who have had three normal Pap smears in a row and none over the past 10 years may cease screening.
"The problem remains that we do not have evidence from national randomized clinical trials to justify these guidelines. We need to focus research efforts on documenting screening efforts in the elderly, examining the benefits of such screening and the rationale behind these screening practices," said Ostbye.
In the absence of concrete cancer screening guidelines in the elderly, Gary Greenberg, M.D., co-author on the paper and a member of Duke's department of community and family medicine, said that providers must make difficult decisions about whom to screen and whom not to screen.
"For some elderly patients, screening may make sense because there is no evidence of other serious illness," said Greenberg. "However, others are clearly being subjected to unnecessary procedures. But without guidelines, doctors must err on the side of caution because of both legal and social consequences of discontinuing screening, even in the most fragile elderly."
The study was funded by the National Institute on Aging. Co-authors on the paper include Donald H. Taylor Jr., Ph.D., Duke University Medical Center and Center for Health Policy, Law and Management at the Terry Sanford Institute of Public Policy, Duke University; and Ann Marie M. Lee of Duke University Medical Center.