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ACOG recommends that annual screening mammograms begin at age 40

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Earlier guidelines suggested that mammography for women 40 to 49 years old could be an annual or biennial activity



Annual mammography screening should be offered to women when they reach 40 years, says a new Practice Bulletin on breast cancer screening from ACOG.1 Previous ACOG guidelines recommended mammograms every 1 to 2 years starting at age 40 and annually beginning at age 50.

According to Jennifer Griffin, MD, MPH, who coauthored the ACOG guidelines, the change in mammography screening for women beginning at age 40 is based on three variables:

  • Incidence of breast cancer. The malignancy remains the second-leading cause of all cancer-related deaths.
  • “Sojourn time” for breast cancer growth (the time it takes for a tumor that is identifiable by mammography to grow big enough to cause symptoms)
  • Potential to reduce the number of deaths from breast cancer.

Although the sojourn time of individual cancers varies, the greatest predictor is age. Women 40 to 49 years old have the shortest average sojourn time (2–2.4 years), whereas women 70 to 74 years old have the longest average sojourn time (4–4.1 years).

“Although women in their 40s have a lower overall incidence of breast cancer compared with older women, the window to detect tumors before they become symptomatic is shorter, on average,” said Dr. Griffin. The 5-year survival rate is 98% for women whose breast cancer tumors are discovered at their earliest stage, before they are palpable and when they are small and confined to the breast. “If women in their 40s have annual mammograms, there is a better chance of detecting and treating the cancer before it has time to spread than if they wait 2 years between mammograms.”

The College continues to recommend annual clinical breast exams (CBE) for women 40 years and older, and CBE every 1 to 3 years for women ages 20 to 39. Additionally, ACOG encourages “breast self-awareness” for women 20 years and older. Breast self-awareness is a woman’s understanding of the normal appearance and feel of her breasts.

“The goal here is for women to be alert to any changes, no matter how small, in their breasts, and report them to their doctor,” said Dr. Griffin. “Although we’ve moved away from routinely recommending [breast self-exams], some women will want to continue doing them and that’s OK.”

Enhanced breast cancer screening, such as more frequent CBEs, annual magnetic resonance imaging (MRI), or mammograms before 40 years of age, may be recommended for women at high risk of breast cancer. Breast MRI is not recommended for women at average risk.

The “downside” of annual screening

“More frequent screening is associated with more false-positive findings,” says Andrew M. Kaunitz, MD, professor and associate chairman of obstetrics and gynecology at the University of Florida College of Medicine in Jacksonville, Fla.

“Due to the high rate of false-positive screens and the large number of screening mammograms needed to prevent the death of one woman in her 40s from breast cancer, the US Preventive Services Task Force recommended in late 2009 that routine screening mammography be deferred until age 50 and that screens be biennial,” he explains.2

“The new ACOG guidance acknowledges these concerns, as well as the potential for anxiety associated with false-positive findings. However, ACOG clearly concluded that, in general, US women cope well with such anxiety.

“When discussing mammograms with women in their 40s, it’s appropriate to acknowledge the high rate of false positives in this age group, which may lead to additional imaging, as well as biopsies,” Dr. Kaunitz suggests. “In my view, we can best serve our patients by making recommendations regarding screening mammograms in a manner that is sensitive to women’s personal values as they attempt to weigh the benefits of earlier and more frequent screening against the risks associated with false-positive screens.”

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