As I’ve discussed in a previous blog, there has been so much controversy and argument over the last few months about when women should begin mammograms and how often women should have them. The whole thing is very controversial. But, here’s an editorial from experts at American Family Physician that I think does one of the best jobs I’ve seen of clearing up the fog for both physicians and our patients. If you’re just interested in the “bottom line,” then scroll down the page to find the recommendations for your age group:
The November 2009 U.S. Preventive Services Task Force (USPSTF) recommendation for breast cancer screening,(1) while sparking much controversy, was not a radical departure from their previous 2002 recommendation.(2) The USPSTF approached the recommendation update with the basic questions of what ages to start and stop screening, what screening test to use, and how often to screen.
When should we start screening?
The 2002 recommendation endorsing mammography encompassed the age range of 40 to 70 years, but stated that “for women aged 40 to 49, the evidence that screening mammography reduces mortality from breast cancer is weaker, and the absolute benefit of mammography is smaller … [It is] difficult to determine the incremental benefit of beginning screening at age 40 rather than at age 50.”(2) The 2002 recommendation endorsed a screening interval of every one to two years.
New evidence, including information from two randomized controlled trials involving breast cancer screening in women 40 to 49 years of age,(3,4, the first paper found here and the second here)allowed the USPSTF to answer the fundamental questions with greater certainty.
The National Institutes of Health’s Cancer Intervention and Surveillance Modeling Network also provided analyses projecting the expected outcomes of different screening strategies.(5)
The incremental reduction of breast cancer mortality that accrues from starting screening at 40 years of age compared with 50 years of age is small, and the false-positive test rate and risk of unnecessary biopsies are highest in this age group. Furthermore, during these 10 years of screening, more than one half of women can expect a false-positive test result.
The proportion of lesions discovered by mammography that are ductal carcinoma in situ (for which the natural history and benefits of treatment are unknown) is largest in this age group.
Although the radiation exposure from a single mammography screening is not large, the cumulative effects of a lifetime of mammography examinations, particularly in the context of other medical imaging, cannot be assumed to be benign.
Some cancers detected and treated would never have progressed to cause harm in a woman’s lifetime (i.e., overdiagnosis).
Given these concerns, in its 2009 update, the USPSTF recommended that “the decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient’s values regarding specific benefits and harms.”(1)
So when should we stop screening?
The USPSTF extended the upper age for which the evidence was sufficient to make a recommendation to 74 years of age. Although no randomized controlled trial data exist to support mammography after 70 years of age, the modeling data strongly support continued benefit, and the USPSTF believed it was prudent to extend the upper age for its recommendation.
At 75 years and older, the uncertainty about net benefit or harm does not support a recommendation for or against screening.
How often should we screen?
Most of the benefit of annual mammography can be achieved with a biennial interval, with a substantial reduction in the number of lifetime mammography examinations and the associated risk. The USPSTF believes that the balance of benefits and harms is best served by a biennial interval.
There is more agreement than disagreement about the value of mammography for breast cancer screening.(6) Mammography does reduce breast cancer mortality, albeit to a lesser extent than many assume, and although imperfect, it is the best screening tool we have.
Controversy about the value of mammography for women in their 40s has long existed,(7) and others have reached similar conclusions to those of the USPSTF.(8)
How can practicing family physicians incorporate this guideline into clinical practice?
Discuss at 40 years of age, encourage at 50 years of age, strongly encourage at 60 years of age, and individualize at 75 years of age.
For women under 40 years of age.
For women 40 to 49 years of age.
For women 50 to 59 years of age.
For women 60 to 74 years of age.
For women 75 years to 84 years of age.
For women 85 years of age or older.