Hi, everyone. I am Dr Kenny Lin. I am a family physician at Georgetown University School of Medicine in Washington, DC, and I blog at Common Sense Family Doctor.
Today I'm going to discuss the new draft US Preventive Services Task Force (USPSTF) recommendations on screening for breast cancer, particularly the assessment in that document in regard to the need for additional imaging for women who have "dense" breasts on mammography.
At a first pass, the USPSTF recommendations look strikingly similar to the previous one from 2009 that sparked a huge controversy and nearly derailed health reform legislation. Once again, the Task Force recommends that average-risk women have screening mammograms every other year beginning at age 50 years and ending at age 74. They found insufficient evidence on the benefits and harms of continuing mammography in women age 75 years or older. And they state that the decision to start screening mammography before age 50 should be individualized; women who value the potential benefits of breast cancer detection more than they do the potential harms of false positives and overdiagnosis may choose to start screening at any time after age 40.
Unlike in 2009, the release of the recommendations received little press, and no Task Force members were summoned before Congress to defend their recommendations. Some readers probably thought that this guideline contained no new information for patients. But the Task Force "buried the lead"; 22 states have now passed laws requiring physicians to notify women whose breasts appear "dense" on mammography that other imaging tests such as ultrasound, MRI, and tomosynthesis are available, and in some cases requiring insurers to pay for these additional screening tests.
What's the issue? Well, in women with dense breasts, who represent nearly half of women being screened, it is harder for radiologists to pick out suspicious lesions from the background of healthy-appearing tissue, and therefore it's harder to detect early breast cancers. These women also have up to twice the risk of average woman of developing breast cancer. So the intent of these laws, many of them supported by patients with dense breasts whose cancers were originally missed on mammography, is to alert women to mammography's limitations so that they can talk to their doctors about additional imaging.
The Task Force systematically reviewed the evidence to support adjunctive imaging for breast cancer in women with dense breasts. They found that not only was there no widely accepted standard for breast density, but that measurements changed over time: up to 1 in 5 women with "dense" breasts on one screening mammogram were reclassified into a "non-dense" category on the next examination. Although ultrasound and MRI found additional cancers, they also led to more false-positive results and biopsies. Most important, no studies examined the effect of additional screenings on breast cancer recurrence rates or deaths.
Not surprisingly, the Task Force concluded that there was insufficient evidence to decide whether the harms of adjunctive imaging are greater than the potential benefits. My opinion is that until more studies are done, family physicians should counsel women whose mammogram reports say they have dense breasts that there is no good reason to do more imaging tests.
This has been Dr Kenny Lin for Medscape Family Medicine. Thank you for listening.
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Cite this: Kenneth W. Lin. Screening Mammography Guidelines: The Change Clinicians Should Know - Medscape - May 29, 2015.