It's Worth Rethinking How Often Women Get Mammograms

In a position paper, the National Breast Cancer Coalition argues that American women undergo too many mammograms.

By The National Breast Cancer Coalition
Photograph: Alexander Raths/iStock

In trying to deal with the toll that breast cancer continues to take in our country, the public has followed the lead of public health officials and increasingly put their faith in screening and early detection, though we have never had good evidence that this would have a significant impact. The over-emphasis on the importance of screening, despite a lack of strong evidence, has been elevated to such a degree that some even equate screening with prevention of breast cancer. The National Breast Cancer Coalition hopes that today’s release of the US Preventive Services Task Force (USPSTF) revised recommendations will put the brakes on this run-away train and will put screening and its limitations into proper perspective.

The revised guidelines were issued by the USPSTF, a government-appointed, independent panel of experts in primary care and prevention that systematically reviews the evidence and develops recommendations for clinical preventive services. Revisions include recommending against universal screening mammography for women aged 40-49, recommending every other year screening for women 50-74, rather than annual screening and recommending against teaching breast self examination.

For over ten years, the National Breast Cancer Coalition has reviewed and analyzed each newly published article looking at the trials of mammography screening. After each analysis, NBCC has continued to take the position that mammography screening has significant limitations and should be a personal choice rather than a public health message. NBCC has also reviewed all articles and studies on breast self examination and historically informed the public that there was no evidence that monthly breast self examination saved lives. When the evidence from well designed prospective randomized trials in addition to that of other studies showed harm and no benefit from this practice, NBCC changed its message accordingly. We continue to affirm those positions and are gratified that the US Preventive Services Task Force has changed their recommendations to be more in line with the existing evidence. Read more about NBCC’s unwavering positions on mammography and breast self examination.

The issues are not simple, but we believe women can comprehend the complexities of breast cancer and screening for the disease. Women deserve to know the facts and have the right to make informed decisions regarding their health care.

The Truth About Breast Cancer and Screening
There is no statistically significant evidence that screening women age 40-49 years reduces breast cancer mortality. The USPSTF now recommends against universal screening mammography for women aged 40 to 49 years. The Task Force changed their recommendation based on a systematic review of randomized clinical trials and on six statistical models of the risks and benefits of mammography screening. A major consideration for the change was the addition of recent results from the only clinical trial designed to specifically evaluate mammography in this age group. The Age trial found no statistically significant difference in breast cancer mortality between those women who were screened during their 40s and those who were not.

- False-positive results and additional imaging as a result of mammography are most prevalent in women aged 40 to 49 years. When screening is started at age 40 years, about 60% more false-positive results have been estimated to occur than if screening is started at age 50 years.

- The evidence for a benefit of mammography after 50 is not strong. To reduce the harm while still maintaining the small benefit, the USPSTF now recommends biennial (every other year) instead of annual screening mammography for women aged 50 to 74 years. The USPSTF concludes that the benefit of screening mammography is maintained by biennial screening, and changing from annual to biennial screening is likely to reduce the harms of mammography screening by approximately 50%, based on the statistical modeling, a systematic review of randomized clinical trials, a population-wide screening program report, and on a community-based study.

- Mammography can miss cancers that need treatment, and in some cases find disease that does not need treatment, leading to overtreatment with toxic therapies. Harms for healthy women who do not have cancer can include unnecessary imaging tests and biopsies, unnecessary exposure to x-ray radiation, and psychological trauma and anxiety.

- All breast cancers are not equal. Some patients will have fast-growing, aggressive tumors while others will have slower-growing, less aggressive tumors that are less likely to metastasize and, therefore, have a better prognosis. Screening is more likely to identify the slower-growing, less aggressive tumors because of longer asymptomatic periods. This “length-time” bias can make screening appear more beneficial than it is. “Lead-time” bias can also contribute to a misrepresentation of the benefit of mammography. If a lethal cancer is found earlier through screening, the patient would appear to live longer because of “lead time.” Screening is not helping patients in these situations live longer, it is only helping them find out about their cancers sooner.

- Breast self-examination (BSE) is ineffective and potentially harmful. Two large, randomized, clinical trials of BSE, both found that women who did BSE were no less likely to die of breast cancer than those who did not do BSE. In both studies, the number of invasive cancers diagnosed in the two groups was about the same, but women in the BSE group had more breast biopsies and more benign lesions diagnosed than did women in the control group. The USPSTF recommends against teaching breast self-examination.

- The USPSTF concludes that there is insufficient evidence to evaluate the benefit of clinical breast examinations.
We encourage women to make informed decisions regarding screening based on the actual evidence. To learn more about the myths and truths concerning breast cancer and screening, and to find out how to take action against this disease, visit StopBreastCancer.org.

First Published Wed, 2009-11-18 13:24

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