Just two weeks after Breast Cancer Awareness Month ended, the US Preventive Services Task Force (USPSTF) dropped a bombshell on patients and health care providers across the country. The Task Force now recommends against routine screening mammography for breast cancer in average-risk women ages 40 to 49.
The American Cancer Society (ACS) promptly issued a statement from Chief Medical Officer Otis W. Brawley, MD: "The [ACS]continues to recommend annual screening using mammography ... for all women beginning at age 40. Our experts make this recommendation having reviewed virtually all the same data reviewed by the USPSTF, but also additional data that the USPSTF did not consider. "
Almost instantly, the debate began. Which set of guidelines will clinicians follow? How confusing will the conflicting recommendations be for patients? And perhaps most alarming—and least controllable—which guidelines will insurers base their coverage on?
USPSTF Assessment
"The decision to start regular, biennial screening mammography before the age of 50," the USPSTF says, "should be an individual one and [should] take patient context into account, including the patient's values regarding specific benefits and harms." The Task Force based its recommendation on "convincing evidence" that while mammography reduces breast cancer mortality, the absolute reduction is greater in women ages 50 to 74 than in those ages 40 to 49. Furthermore, the USPSTF says there is "moderate certainty" that the net benefit of mammography screening in the younger age-group is small.
Nelson et al performed a systematic literature review for the USPSTF (Ann Intern Med. 2009; 151[10]:727-737). This analysis revealed a pooled relative risk for breast cancer mortality among women screened with mammography of 0.85 in those ages 40 to 49 and 0.86 in those ages 50 to 59. The researchers also found a "number needed to invite [for screening] to prevent one breast cancer death" of 1,904 for women ages 39 to 49 and 1,339 for those ages 50 to 59. The latter data show, according to the USPSTF, that "the absolute risk reduction ... is greater" for women in the older age-group.
Also published in the same issue of Annals of Internal Medicine were results from a related study by the Breast Cancer Working Group of the Cancer Intervention and Surveillance Modeling Network (2009;151[10]:738-747). Mandelblatt et al used six models to predict the benefits and harms of 20 different mammography screening strategies (with various ages of initiation and cessation, as well as different screening frequencies [annual or biennial]).
The Working Group found that "screening every other year from ages 50 to 69 ... is an efficient strategy for reducing breast cancer mortality." Beginning to screen at age 40 provided "additional, albeit small, reductions" that equated to a median one additional breast cancer–related death averted per 1,000 women screened on an annual basis. Annual screening beginning at age 40 also provided a median 33 life-years gained per 1,000 women screened. The Working Group also reported, however, that the rate of false-positive results for annual screening of women from age 40 through 69 was 2,250 per 1,000 women screened.
Based on these and other findings, the USPSTF concluded that "the additional benefit gained by starting screening at age 40 ... rather than at age 50 ... is small, and that moderate harms from screening remain at any age."
The Backlash
According to Brawley's statement, the ACS is aware that "the overall effectiveness of mammography increases with increasing age." However, he added, screening women starting at age 40 does save lives.
"With its new recommendations, the USPSTF is essentially telling women that mammography at age[s] 40 to 49 saves lives; just not enough of them," Brawley stated.
The ACS statement cites recent data indicating that about 17% of breast cancer deaths occur in women diagnosed during their 40s, and 22% occur in those diagnosed during their 50s. Brawley said that ACS staff, members, and supporters "overwhelmingly believe the benefits of screening women ages 40 to 49 outweigh its limitations."
In his online cancer blog (www .cancer.org/aspx/blog), J. Leonard Lichtenfeld, MD, MACP, Deputy Chief Medical Officer of ACS, wrote at length about the new recommendations from USPSTF. He referenced the modeling study by Mandelblatt and colleagues (among other research), noting that depending on which model was used, breast cancer mortality was reduced by as much as 54% when women were screened annually between ages 40 and 84; by comparison, the reduction was 28% when women ages 50 to 74 were screened every two years. Other models revealed little or no difference, he acknowledged.
Lichtenfeld summarized the research this way: "You could get somewhere between 70% and 99% of the benefit of screening mammograms (that is, reducing deaths from breast cancer) while reducing the harms by about 50% if you started screening at age 50 and did it every two years, as compared to starting at age 40 and doing it every year."