Guideline: Mammography optional in women 40-49

Clinical Question: Should screening mammography be used in women between the ages of 40 years and 49 years?

Bottom Line: In a break from other authorities, this evidence-based guideline from the American College of Physicians (ACP) makes no absolute recommendation for or against the screening of women between the ages of 40 years and 49 years. Instead, it recommends routine, periodic risk assessment, as well as discussions with individuals regarding the benefits and harms of screening mammography.(LOE = 1a)

Reference: Armstrong K, Moye E, Williams S, Berlin JA, Reynolds EE. Screening mammography in women 40 to 49 years of age: a systematic review for the American College of Physicians. Ann Intern Med 2007;146:516-526. [Free full-text Annals article online] [Medline® abstract]

Study Design: Practice guideline
Funding: Foundation
Setting: Various (guideline)

Synopsis

Here's an underappreciated fact: More women between the ages of 40 and 49 years die from heart disease (6800) than from breast cancer (5000) each year. To develop this guideline, the ACP researchers analyzed the latest meta-analyses on this topic and considered an additional study that was subsequently published. The main findings: There are 7% to 23% fewer deaths due to breast cancer over an average of 14 years with screening starting at age 40; an overall mortality reduction hasn't been shown; screening increases rates of mastectomy; rates of ductal carcinoma in situ diagnosis skyrocket 7-fold with increased screening, representing 25% of the diagnoses of "cancer" in this age group; and, 20% to 56% of women will have a false-positive diagnosis when tested yearly for 10 years. In addition to recommending more research, the authors made 3 recommendations:

(1) The decision of whether to order a screening mammography should be made on an individual basis, taking into account the benefits, harms, risk profile, and patient preferences.

(2) Clinicians should update a woman's risk profile every 1 to 2 years. Risk factors for all women include a family history of breast cancer, earlier menarche, later age at time of first birth, and a history of breast biopsy. In addition, women aged 40 to 49 years with certain risk factors are at higher risk than the average 50-year-old woman, including 2 first-degree relatives with breast cancer and 2 previous breast biopsies. The Gail Risk Model Calculator (available in InfoRetriever) can be used to determine an individual woman's risk.

(3) Clinicians should discuss the potential benefits and harm of screening mammography with their patients. The most recent meta-analysis found a reduction in breast cancer-related mortality by 15%, although the confidence interval was wide (as little as 1% risk reduction and as much as 27% risk reduction). A more recent randomized trial, which was not included in the meta-analysis, found no statistically significant reduction in risk of breast cancer mortality. Potential harms include false-positive results, which are as high as 20% to 56% over the course of 10 mammograms, as well as the anxiety associated with the false-positives. Other theoretical risks include discomfort with the procedure. The authors found no evidence of increased radiation-induced cancer or overdiagnosis due to screening.

Written by Cung Pham, MD

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