What is the evidence on screening mammography for women in their 40s?

Journal of Family Practice, July, 2007 by K. Armstrong, E. Moye, S. Williams, J.A. Berlin, E.E. Reynolds

* Clinical question

What is the American College of Physicians' (ACP) position on screening mammography for women between the ages of 40 and 49 years?

* Bottom line

The ACP makes no absolute recommendation for this age group, but recommends routine risk assessment every 1 to 2 years, and discussing the benefits and harms of screening mammography with patients.

Level of evidence

1a: Systematic review (with homogeneity) of randomized controlled trials

Study design

Practice guideline

Funding

Foundation

Setting

Various (guideline)

Synopsis

To develop its guideline, ACP researchers analyzed meta-analyses on this topic and considered an additional study, which was subsequently published.

Key findings

* 7% to 23% fewer deaths due to breast cancer over an average of 14 years with screening starting at age 40; however, an overall mortality reduction hasn't been shown.

* 20% to 56% of women will have a false-positive diagnosis when tested yearly for 10 years.

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 40 to 49 years of age with certain risk factors are at higher risk than the average 50-year-old woman--these factors include 2 or more first-degree relatives with breast cancer and having at least 2 previous breast biopsies. The Gail Risk Model Calculator 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.

Potential benefits

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 [not included in the meta-analysis] found no statistically significant reduction in risk of breast cancer mortality.)

Potential harms

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.

FAST TRACK

Update a woman's risk profile every 1 to 2 years

* Gail Risk Model Calculator: www.cancer.gov/bcrisktool

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.