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Mammographic Screening for Asymptomatic Women

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At its 1988 Annual Meeting, the American Medical Association (AMA) adopted Report F of the Council on Scientific Affairs (CSA), "Mammographic Screening in Asymptomatic Women Aged 40 Years and Older." The recommendations in this report were adopted as Policy H-525.993 (AMA Policy Compendium), which was reaffirmed at the 1994 Annual House of Delegates meeting. This policy calls for annual mammography screening and clinical breast examination for all women, beginning at age 50 years. Citing the uncertainty on this subject, this policy also called for screening mammography and clinical breast examinations for women aged 40 to 49 years every one to two years. Policy 525.993 also called for periodic reconsideration of those recommendations, as more epidemiological and cost data become available. 

The CSA informational report, "The Advisability of Screening Younger Women for Breast Cancer" (CSA Report 9, A-97, Summary), reviewed the continuing controversy about the benefits of mammographic screening for women 40 to 49 years of age. In this report, the CSA reviewed the scientific evidence on the efficacy of mammograms for women in this age group and concluded, as did others, that the evidence supporting the efficacy of mammography screening for this age group was, at that time, less definitive than that supporting its efficacy in older women. 

The 1997 report did not recommend any change in AMA policy on mammography screening. At the time, many medical and health organizations were updating their positions on the issues. This report briefly reviews major studies released since 1997, describes the updated positions of some other key organizations, and provides CSA recommendations for updating AMA policy.

Recent Research

A recent report by Heimann et al,¹ which studied a large series of women with stage I and II breast carcinoma with a mean follow-up of 43 months, concluded that mammography reduces breast cancer mortality in women aged 40 to 49 years and justifies the economic and other costs. For mammographically detected tumors, there is no significant difference in recurrence-free survival (RFS) in women under age 50 versus women over age 50. However, for tumors that are clinically detected there is a difference in RFS for women under age 50 versus women over age 50. Tumors in women under 50 years of age appear to be more aggressive. Mammography in women under age 50 would detect these tumors earlier and confer better RFS for these women. 

Similar findings that support annual mammography are reflected in the report from Memorial Sloan-Kettering by Cody.² In this retrospective study of 1,096 consecutive patients with breast cancer, diagnosis was made principally by mammography in 28.8% of the younger (<50 years) and in 42.4% of the older (>50 years) patients treated most recently (1989 to 1993). Tumors that were found primarily by mammography had important differences from those found by patient self-examination or physician examination; ie, "(i) 95% of the patient self-exams and 56% of physician exams were negative; (ii) tumor size was significantly smaller (P <0.00005); (iii) lymph nodes more often were negative (P=0.0002); and (iv) histology was more likely to be either in-situ or microinvasive (P<0. 00005)."  ² Interestingly, the findings were equally true for younger and older patients. These findings support extending the use of screening mammography in women <50 years of age. 

Further support for mammography in women <50 years of age, comes from a 1997 randomized trial of over 11,000 women aged 39 to 49 years in Sweden. This study found a 45% reduction in breast cancer mortality for women who received mammographic screening every 18 months compared to a control group who were not screened until the 5th interval (6 to 7 years after randomization).³ 

Cost effectiveness of screening mammography has been found to be within the range of other diagnostic procedures when expressed as marginal cost per year of life saved.  ⁴

Policy Positions of Other Organizations

In January 1997, the National Institutes of Health (NIH) convened a consensus conference to consider the available scientific information on breast cancer screening for women aged 40 to 49 years. The purpose of the conference was to provide a public forum to review the costs and benefits of mammography screening for women in their 40s. In the resulting statement (March 20, 1997), the NIH consensus panel concluded: "The data currently available do not warrant a universal recommendation for mammography for all women in their forties. Each woman should decide for herself whether to undergo mammography." In additional commentary, the consensus statement does state that for "women in their forties who choose to have mammography performed, costs of the mammograms should be reimbursed by third party payors or covered by health maintenance organizations."⁵

The National Cancer Institute (NCI) reviewed the findings of the NIH consensus panel but took a policy position that diverged from the panel's recommendation.⁶ Currently, the NCI supports regular mammographic screening of women aged 50 to 69 years, which studies indicate will lead to reduction in breast cancer deaths of 25% to 30% 10 to 12 years later. NCI supports regular screening every 1 to 2 years for women 40 to 49 years of age. NCI further recommends that women who have an increased risk of breast cancer should seek specific medical advice on when to begin and how often to have mammograms. 

The American College of Obstetricians and Gynecologists continues to recommend mammograms every one to two years for women between the ages of 40 and 49 years.⁷

In March 1997, the American College of Radiology  ⁸ and the American Cancer Society  ⁹ revised their recommendations, changing their policy from screening every one to two years for women between age 40 and 49 years to annual mammography for all women, beginning at age 40. 

Discussion 

Counseling an individual patient based on the results of population-based studies always involves some judgment about the circumstances of that particular patient (taking into account family history and other associated disease risk, eg, age at first pregnancy). General recommendations of medical societies and the NIH can provide assistance in cases where the epidemiological evidence is clear. Current epidemiological evidence now demonstrates the efficacy of mammography screening for detecting cancer in women in their 40s.^1-4 Cost effectiveness of screening mammography has been found to be within the range of other diagnostic procedures when expressed as marginal cost per year of life saved.⁹

RECOMMENDATIONS 

The following statements, recommended by the Council on Scientific Affairs, were adopted by the AMA House of Delegates as AMA policy at the 1999 AMA Annual Meeting. 

1. AMA Policy 525.993 (AMA Policy Compendium) is amended to state: "(1) The AMA favors participation in and support of the efforts of the professional, voluntary, and government organizations to educate physicians and the public regarding the value of screening mammography in reducing breast cancer mortality. (2) The AMA advocates remaining alert to new epidemiological findings regarding age-specific breast cancer mortality reduction following mammography screening. (3) Based on recent summary data the AMA recommends annual screening mammograms and continuation of clinical breast examinations in asymptomatic women 40 years and older. (4) The AMA encourages the periodic reconsideration of these recommendations as more epidemiological data becomes available. (5) The AMA supports seeking common recommendations with other organizations. (6) The AMA reiterates its longstanding position that all medical care decisions should occur only after thoughtful deliberation between patients and physicians."  
2. AMA Policy 525.982 ("The AMA supports continued efforts to develop a multicenter breast screening trial to determine the optimal mammographic screening interval for women ages 40-49.") is rescinded.