Although the majority of women (51%) age 80 years or older were screened with mammography, fewer than 2% potentially benefited. Moreover, potentially benefitted was liberally defined as any women who was diagnosed with early-stage disease, accepted treatment, and lived 2 years after diagnosis (). Many women (12.5%) experienced burdens from screening including additional tests (n = 110), false reassurance from false-negative mammograms (n = 3), or refusal of work-up after an abnormal mammogram (n = 8). Eight women who were screened were diagnosed with DCIS and were subject to the anxiety of being diagnosed and burdened with decision-making around treatment for a disease that is unlikely to progress during their lifetime. In contrast, three women (0.3%) who were not screened may have been harmed from not being screened since they experienced a recurrence or were diagnosed with late-stage disease and died as a result of breast cancer. Women age 80 years or older and their clinicians can use these data to decide whether the potential benefits of mammography screening outweigh the burdens and potential harms of not being screened.
Despite the uncertainty of a mortality benefit from mammography screening for women age 80 years and older, some experts argue that these women should be screened to prevent large tumors that may require more aggressive therapy and may be more likely to recur than smaller tumors.7,19
We did not find a significant difference in stage at diagnosis or in breast cancer recurrence or treatments received between women who were screened and those who were not screened. However, this was an observational study and it may be that the women who were screened were at greater risk of breast cancer. It may also be that many of the women in our study who were not being screened with mammography were receiving clinical breast examinations (CBEs). Nearly one half of the women who were diagnosed with breast cancer in the unscreened group had their tumors detected by clinical exam. Perhaps regular CBEs after age 80 years detect tumors early enough to avoid significant morbidity without detecting as much clinically insignificant disease as mammography screening.20
We and others have found that very few women age 80 years or older die of breast cancer. Woloshin et al21
found using population data that lower than 2% of these women die of breast cancer. This is higher than our rate of 0.2%. Woloshin et al21
did not exclude women with a history of breast cancer before age 80 years, suggesting that the majority of women dying of breast cancer in their 80s are those who have a history of the disease by age 80 years.
Some women in our study may have benefitted from screening due to the reassurance they experienced after a negative test.22
However, there are likely more cost-effective ways to offer older women reassurance about their health, especially since many effective preventive health measures are underutilized among these women (eg, immunizations, exercise).23
Most cost-effective analyses have found that the positive effects of mammography screening balance with the negative effects around age 80 years.24,25
Our findings also suggest overuse of mammography screening among elderly women since nearly 10% of those who were screened were screened within 2 years of their death. One reason for overscreening may be due to the fact that Medicare pays for annual mammography for all women age 80 years or older regardless of their health. The American Geriatrics Society offers a more thoughtful approach to screening.26
They encourage clinicians to offer screening to women age 85 years or younger with at least 5 years life expectancy after an individualized review of the potential benefits and risks of screening and a discussion of patient preferences. The American Geriatrics Society recommends that mammography be reserved for women older than 85 in excellent health and functional status or those who strongly believe that they will benefit either through piece of mind or improved quality of life. The data from our study can be used to help women age 80 years or older understand the potential benefits and burdens of screening and what would likely occur if they chose not to be screened to allow for informed, preference based decision making.
There are several important limitations to this study. Since this study is a retrospective medical record review, some missing data are inevitable. We were unable to confirm that 295 women (15%) were alive at the end of the study since they had left the practice. However, there was no report of their death in the NDI. The study is not powered to detect a significant difference in breast cancer mortality between screened and unscreened women. However, even large database studies have been unable to detect a mortality difference for breast cancer screening among women age 80 years or older with comorbidity.8,9
We only have comorbidity data or receipt of CBEs on a subset of women. Finally, our results may not be generalizable to older women outside of MA. However, our study did include a large number of women age 80 years or older from both academic and community primary care sites that were ethnically diverse. Also, our false positive rate is within the range (5% to 23%) reported by other studies that included women of all ages.17,27–29
The majority of women age 80 years or older are screened with mammography yet few benefit. Meanwhile, 12.5% experience a burden from screening. The data from this study can be used to inform elderly women's decision making and potentially lead to more rational use of screening.