Interpreting the U.S. Preventive Services Task Force Breast Cancer Screening Recommendations for the General Population

November 16, 2009

What are the new recommendations from the U.S. Preventive Services Task Force (USPSTF)?

The following recommendations for the general population appear in the November 17, 2009, issue of Annals of Internal Medicine (see www.annals.org):

  • The USPSTF recommends against routine screening mammography in women aged 40 to 49 years. 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. (grade C recommendation)
  • The USPSTF recommends biennial screening mammography for women aged 50 to 74 years. (grade B recommendation)
  • The USPSTF concludes that the current evidence is insufficient to assess the additional benefits and harms of screening mammography in women 75 years or older. (grade I statement)
  • The USPSTF recommends against teaching breast self-examination (BSE). (grade D recommendation)
  • The USPSTF concludes that the current evidence is insufficient to assess the additional benefits and harms of clinical breast examination (CBE) beyond screening mammography in women 40 years or older (grade I statement)

What were the previous (2002) USPSTF recommendations?

  • The USPSTF recommended screening mammography, with or without CBE, every 1-2 years for women aged 40 and older. (grade B recommendation)
  • The USPSTF concluded that the evidence was insufficient to recommend for or against routine CBE alone to screen for breast cancer. (grade I statement)
  • The USPSTF concluded that the evidence was insufficient to recommend for or against teaching or performing BSE. (grade I statement)

What do the USPSTF letter grades mean?

The USPSTF's recommendations are based on its assessment of net benefit—identified benefits minus identified harms. The USPSTF will only make a recommendation if it judges the available evidence to be of high enough quality that it can have high or moderate certainty as to the magnitude of the net benefit.

Interventions that are deemed to have substantial net benefit receive an A grade; interventions with moderate to substantial net benefit receive a B grade; interventions with small net benefit receive a C grade; interventions that have no net benefit (have harms that exceed the benefits) receive a D grade. If the evidence does not meet USPSTF standards, an "I statement" is issued.

Each letter grade is accompanied by a suggestion for practice. For A and B recommendations, the suggestion is to "offer/provide this service." For C recommendations, the suggestion is to "offer/provide this service only if other considerations support offering or providing the service in an individual patient." For D recommendations, the suggestion is to "discourage the use of this service." For I statements, the suggestion is to "read the clinical considerations section of USPSTF Recommendation Statement. If the service is offered, patients should understand the uncertainty about the balance of benefits and harms."

Grade C recommendations highlight the need for individualized decision making that considers the patient's own assessment of benefits and harms. The American College of Obstetricians and Gynecologists strongly supports shared decision making, and in the case of screening for breast cancer it is essential. Surveys have shown that women are more concerned about their risk of breast cancer than heart disease, which is more common. Many women, after weighing the benefits and risks for their own particular situation, will choose to have screening mammography.

What are the current recommendations from The American College of Obstetricians and Gynecologists?

The American College of Obstetricians and Gynecologists continues to recommend the following services:

  • Screening mammography every 1-2 years for women aged 40-49 years
  • Screening mammography every year for women aged 50 years or older.
  • BSE; BSE has the potential to detect palpable breast cancer and can be recommended.
  • CBE every year for women aged 19 or older

What is the College doing in response to the new recommendations?

The College, as a partner organization of the USPSTF, reviewed the draft recommendation statement and expressed concern regarding the implications of recommending against routine screening mammography for women in their 40s.

The College is continuing to evaluate in detail the new USPSTF recommendations and the new evidence considered by the USPSTF. The new recommendations and the evidence on which they were based will be reviewed by College committees that make recommendations on screening for breast cancer. Should the College update its guidelines in the future, Fellows would be alerted and such revised guidelines would be published in Obstetrics & Gynecology.

Why did the USPSTF recommend against routine mammography for women in their 40s?

The new USPSTF recommendations are based on a systematic evidence review by Heidi D. Nelson, MD, MPH, and colleagues and a modeling study by Jeanne S. Mandelblatt, MD, MPH, and colleagues that were published in the same issue of Annals of Internal Medicine as the recommendation statement. Based on these analyses, the 2009 USPSTF judged that although women in their 40s and women in their 50s benefit equally from routine screening mammography, women in their 40s experience greater harms from screening than do women in their 50s. Therefore, the USPSTF recommended routine screening for women aged 50-74 years but recommended against routine screening for women in their 40s.

The USPSTF's evaluation of the evidence found that the benefit to women in their 40s was virtually the same as the benefit to women in their 50s. The relative risk of breast cancer mortality for women randomly assigned to mammography screening was 0.85 in women aged 39-49 years and 0.86 in women aged 50-59.

Rather than benefit from screening, women without cancer who undergo mammography, additional imaging, and biopsies may incur harm. These outcomes were more common in women in their 40s (see Table). In addition, because the prevalence of breast cancer is higher in women in their 50s and because younger women are more likely to have dense breasts that may be difficult to assess on mammography, women in their 40s had more false-positive mammograms and underwent more additional imaging than women in their 50s.

Table. Age-Specific Screening Results from the Breast Cancer Surveillance Consortium

Age Group (Y) No. of procedures to diagnose one case of invasive breast cancer*
Mammography Additional Imaging Biopsy
40-49 556 47 5
50-59 294 22 3

*Data are from a single screening round in regularly screened women. Because the Breast Cancer Surveillance Consortium incompletely captures additional imaging and biopsies, these rates may be underestimates.

Data from: Nelson HD, Tyne K, Naik A, Bougatsos C, Chan BK, Humphrey L. Screening for breast cancer: an update for the U.S. Preventive Services Task Force. Ann Intern Med 2009;151:727-37.

The number needed to invite for screening (over several rounds of screening and at least 11 years of follow-up) to prevent one breast cancer death in women aged 39-49 was 1,904, compared with 1,339 in women aged 50-59.

The USPSTF also considered pain and psychologic responses as harms. The USPSTF notes that "anxiety, distress, and other psychosocial effects. . . fortunately are usually transient, and some research suggests that these effects are not a barrier to screening. . . Other potential harms, such as pain caused by the procedure, exist but are thought to have little effect on mammography use."

The Mandelblatt modeling study assessed six separate models of the effects of screening mammography using the National Cancer Institute's Cancer Intervention and Surveillance Modeling Network (CISNET). It states: "If the goal of a national screening program is to reduce mortality in the most efficient manner, then programs that screen biennially from age 50 years to age 69, 74, or 79 years are among the most efficient on the basis of the ratio of benefits to the number of screening examinations. If the goal of a screening program is to efficiently maximize the number of life-years gained, then the preferred strategy would be to screen biennially starting at age 40 years."

How might women be affected by the new recommendations against routine screening mammography for women in their 40s?

U.S. Census data demonstrate that there were 22,327,592 women aged 40-49 years in the United States as of July 1, 2008. Based on Surveillance Epidemiology and End Results Program (SEER) data, breast cancer deaths expected over 10 years were estimated at 204 deaths per 100,000 women aged 40-49 years (including both screen-detected and nonscreen-detected breast cancer). This 10-year death rate leads to an estimate of 45,492 deaths of U.S. women aged 40-49 years from breast cancer over 10 years. With a relative risk of 0.85 for breast cancer mortality for women in their 40s screened by mammography, an estimated 38,668 deaths would occur in a screened population over 10 years, approximately 6,800 fewer deaths than expected with the 10-year death rate. The fewer deaths expected with screening compared to the predicted deaths demonstrates the significant benefit of screening on mortality in this age group.

Why did the USPSTF recommend against teaching BSE?

The new USPSTF recommendations are based on a systematic evidence review by Heidi D. Nelson, MD, MPH, and colleagues published in the same issue of Annals of Internal Medicine. This systematic evidence review identified two studies published since the 2002 recommendations. These studies found that teaching BSE did not reduce breast cancer mortality but resulted in additional imaging procedures and biopsies. Therefore, the USPSTF recommended against teaching BSE on the grounds that it has no benefit for women but places them at risk of harm.

Who uses the USPSTF recommendations?

The main audience for the USPSTF recommendations is the primary care clinician. The congressional mandate establishing the USPSTF charges it with reviewing "the scientific evidence related to the effectiveness, appropriateness, and cost-effectiveness of clinical preventive services for the purpose of developing recommendations for the health care community."

However, although the USPSTF recognizes that its recommendations also have relevance for and are widely used by policymakers, managed care organizations, public and private payers, quality improvement organizations, research institutions, and patients, it also recognizes that its recommendations are only part of what needs to be considered in setting health care policy. The disclaimer that accompanies these new recommendations reads: "The USPSTF recognizes that clinical or policy decisions involve more considerations than this body of evidence alone. Clinicians and policymakers should understand the evidence but individualize decision making to the specific patient or situation."

How will the USPSTF recommendations be used in health care reform?

Health care reform legislation being considered in the House and Senate seeks to ensure coverage of preventive services as part of a basic benefits package in all health insurance plans, as well as patient cost-sharing protections for these services. In determining which services should be covered, the bills rely heavily on the USPSTF recommendations. At a minimum, covered preventive services would be those that receive an A or B grade from the USPSTF.

It is vital that covered preventive services not be limited solely to USPSTF grade A and B recommendations. The USPSTF has not issued recommendations for many vital preventive services in women's health care, such as preconception care, family planning counseling and services, and bundled services such as the annual well-woman examination. The USPSTF only makes and updates a handful of recommendations each year, far too few to address clinically appropriate preventive services that ought to be covered by any plan.