By Amy Bethea, MD, Roper Radiology
There was much media coverage, confusion and discussion surrounding the release of revised breast cancer screening guidelines presented by the U.S. Preventive Services Task Force (WSPSTF) this past fall. In November 2009, this independent panel of primary care physicians and non-physician scientists, a panel that did not include radiologists, surgeons, radiation or medical oncologists, presented revised guidelines for screening mammography.
Based primarily on cost/benefit analysis, their conclusions were:
- No routine mammography screening for women 40 - 49 years old.
- Biannual screening for ages 50 - 74.
- Insufficient data on clinical exam benefits.
- Do not instruct patients on self breast exam.
- Insufficient data to favor digital mammography.
The American Cancer Society, American College of Radiology and the Society of Breast Imaging have adamantly opposed these guidelines. When using the same data and more, different conclusions were reached concerning risks vs benefits. There was universal agreement that screening with mammography reduces breast cancer mortality in women 40 – 74, with age-specific benefits varying depending on specific trials evaluated. And it is a well known fact that mammography has its limitations, including false negatives and false positives – some cancers will be missed, unnecessary biopsies will be performed, and that the overall effectiveness of screening mammography does increase with increasing age, but the limitations do not change the fact that breast cancer screening using mammography starting at age 40 saves lives and that it is worth the expense and inconvenience.
Most recent data shows that approximately 17% of breast cancer deaths occurred in women diagnosed in their 40s and 22% occurred in women diagnosed in their 50s. Shared statistics show a 40-50% mortality reduction for women ages 40 to 75 screened in Sweden and British Columbia with 30-40% mortality reduction in women between 40 and 49 years of age. Although the USPSTF implied that 1904 women between the ages of 40 and 49 needed to be screened to save one life, this was actually the number invited to screen, not how many were actually screened. The true number of women actually screened to save one life was between 726 and 952 in this age group. There has been nearly 30% reduction in breast cancer mortality since 1990, attributed both the mammographic screening and advances in treatment.
Although the USPSTF guidelines are not legally binding, they could be gaining a legislative foothold and if Medicare stops covering breast screenings for women under 50, other insurance carriers will follow. The risk of following the USPSTF guidelines is that fewer women will be screened at longer intervals and though this will save money in the screening, patients will present with later stage disease, and increased morbidity and mortality.
For these reasons, Roper St. Francis Cancer Care and its Breast Care program follow the current American Cancer Society guidelines for mammography screening, as follows:
- Annual mammograms beginning at age 40 and continuing as long as the woman is in good health.
- Clinical breast exam should be part of a periodic health exam – about every 3 years in women ages 20-40 and annually after age 40.
- Breast self exam is an option for women starting in their 20s.
- Women at high risk (greater than 20% lifetime risk) in addition to mammography, should get an annual screening breast MRI. In women with moderate risk (15-20% lifetime risk) benefits and limitations should be discussed with their physician and in patients with <15% lifetime risk, breast MRI is not recommended.
Mammography is not 100% sensitive or specific but it is the only screening method proven to have a positive impact on survival in women aged 40 to 74.