In a look at breast cancer mortality within three pairs of European countries, Autier and colleagues concluded that screening did not directly contribute to the observed reduction in mortality.3 The country pairs were:
- Northern Ireland and the Republic of Ireland
- the Netherlands and Belgium/Flanders
- Sweden and Norway.
Each pair of countries offered comparable health-care services, had a similar prevalence of risk factors for breast cancer mortality, and experienced a similar reduction in breast cancer mortality from 1989 to 2006. However, implementation of mammography screening in these paired countries differed by approximately 10 to 15 years.
Last, in a meta-analysis from the United Kingdom, where women 50 to 70 years old are invited to be screened every 3 years, an independent panel concluded that mammography reduced breast cancer deaths but also led to overdiagnosis.4 Although the analysis included studies “with many limitations,” its findings suggest that one breast cancer death would be prevented for every three cases of overdiagnosis.
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Improvements are expected
Thanks to a recent analysis of the breast cancer genome, in the future it may become possible to identify which breast tumors are likely to progress. Such an advance would allow clinicians to recommend treatment strategies in a highly selective fashion.5
WHAT THIS EVIDENCE MEANS FOR PRACTICE
The findings from this recent study make me that much more comfortable following the USPSTF guidelines for screening mammography. For average-risk women in their 40s, I do not push screening but am happy to arrange it if my patient would feel more comfortable being screened. However, if a woman in her 40s is at increased risk (eg, first-degree relative with breast cancer), I encourage her to undergo annual screens.
As for average-risk women in their 50s and older, I find that most of my patients continue to prefer annual screening, but I am supportive of screening every 18 or 24 months in this population.
Some ObGyns may wonder if they could be exposed to medicolegal risk if they do not follow ACOG guidelines. For example, what would happen if a patient in her 40s who has not been screened were diagnosed with breast cancer? I am not an attorney, but I know that the USPSTF guidelines represent a credible (many would say authoritative) resource for guidance related to mammography screening. Speaking of the USPSTF, it is worth pointing out that this body is made up of 16 primary care and public health physicians (including one ObGyn) who have no stake in regard to breast imaging. (See http://www.uspreventiveservicestaskforce.org/members.htm.)
It’s my view that radiologists who provide screening breast imaging services can play an important role in educating women about the pros and cons of mammography. Looking to the future, perhaps women checking in for a screening mammogram will be asked to review and sign a document that clearly explains benefits (eg, reducing mortality through early diagnosis) as well as risks (eg, the occurrence and consequences of overdiagnosis: finding cancers that are destined not to not to cause advanced disease).
ANDREW M. KAUNITZ, MD
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