ACOG Recommends Annual Mammograms Begin at Age 40 Years

Laurie Barclay, MD

July 20, 2011

July 20, 2011 — Mammography screening should be offered annually to women beginning at age 40 years, according to new breast cancer screening guidelines issued by the American College of Obstetricians and Gynecologists (ACOG). The new Practice Bulletin, entitled "Breast Cancer Screening," is published in the August 2011 issue of Obstetrics & Gynecology. These guidelines replace the 2003 ACOG recommendations, which were that women should have mammograms every 1 to 2 years beginning at age 40 years, and every year beginning at age 50 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 guidelines coauthor Jennifer Griffin, MD, MPH, in a news release. "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 two years between mammograms."

Specific ACOG Recommendations

The only Level B specific recommendation in the new Practice Bulletin, based on limited and inconsistent scientific evidence, is the following:

  • Women 40 years and older should be offered screening mammography annually. The basis for this recommendation includes the incidence of breast cancer, the sojourn time for breast cancer growth, and the potential reduction in breast cancer mortality risk associated with early detection. Tumors detected at their earliest stage, before they are palpable and when they are small and confined to the breast, are associated with a 98% 5-year survival rate. Sojourn time refers to the period between when a breast cancer may first be detected by a mammogram and before it enlarges sufficiently to become symptomatic. The sojourn time of individual cancers varies, but age is the best predictor, with the shortest average sojourn time (2 - 2.4 years) in women aged 40 to 49 years, and the longest average sojourn time (4 - 4.1 years) in women 70 to 74 years old.

Additional Level C specific recommendations in the new Practice Bulletin, based primarily on consensus and expert opinion, are the following:

  • Women 40 years and older should undergo annual clinical breast examination (CBE) by their physician, as studies suggest that CBEs assist in early detection of breast cancer, especially when used along with mammograms.

  • Women 20 to 39 years old should undergo CBE every 1 to 3 years, although CBE in this age group is of unclear benefit.

  • All women should be encouraged to practice breast self-awareness, which may include breast self-examination. Any changes that women detect in their breasts should be reported to their healthcare providers. Breast self-examination is performed regularly (usually monthly) in a systematic fashion, whereas breast self-awareness refers to women understanding the normal appearance and feel of their breasts, but without a specific interval or systematic examination technique. "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," Dr. Griffin said. "Although we've moved away from routinely recommending breast self-examinations, some women will want to continue doing them and that's OK."

  • Women should be informed of the predictive value of screening mammography, including the potential for false-positive and false-negative results. They should also be counseled that results of screening may lead to recommendations for additional imaging tests or biopsies.

  • Enhanced screening may be offered to women estimated to have a lifetime risk for breast cancer equal to or exceeding 20%, on the basis of risk models relying largely on family history (eg, BRCAPRO, BODACEA, or Claus), but who are either untested or test negative for BRCA gene mutations. Enhanced breast cancer screening may include more frequent CBEs, annual magnetic resonance imaging scans, or mammograms beginning before age 40 years.

  • For women at average risk for the development of breast cancer, a breast magnetic resonance imaging study is not recommended for screening.

  • Enhanced screening should be recommended for women testing positive for BRCA1 and BRCA2 mutations. Strategies to reduce risk should also be discussed with these women.

Compared with film mammography, digital mammography had a slightly higher detection rate, particularly for women 60 years or younger, based on a recent meta-analysis of data from 8 large randomized trials.

The ACOG guidelines did not reach a consensus on the upper age limit for mammograms, but the potential benefits of screening decrease with advancing age, compared with potential harms of overtreatment. Dr. Griffin suggested that women 75 years and older discuss with their clinician the advisability of continued mammography screening.

"The good news is that fewer women are dying from breast cancer because of earlier detection and improved treatments," said Gerald F. Joseph, Jr, MD, ACOG vice president for practice activities.

American College of Radiology Responds

The updated ACOG guidelines agree with recommendations issued by the American College of Radiology (ACR), the Society of Breast Imaging, the American Cancer Society, and the American Society of Breast Disease. However, all of these differ from those of the United States Preventive Services Task Force (USPSTF), which states that among women 40 to 49 years, only those with a family history of breast cancer or other high-risk factors should be screened and that women 50 to 74 years should be screened every 2 years.

"The new ACOG recommendations are just another affirmation of the guidelines that the ACR and the American Cancer Society have stood by throughout the controversy," Carol Lee, MD, head of the Communications Committee of the Breast Commission of the ACR and a practicing radiologist in New York, NY, told Medscape Medical News. "The new Practice Bulletin really does not cover any new data, but affirms and endorses the interpretation of that data by other professional societies, and we find this very gratifying. Our hope is that the new ACOG guidelines will emphasize the importance of annual mammography beginning at age 40 and that mammography saves lives."

The ACR notes that the USPSTF relied largely on computer modeling to reach its conclusions but that there are no scientific data to support age 50 years as a biological threshold for screening. The ACR also suggests that the focus of the USPSTF was to reduce false-positive study results, most of which can be resolved by a few additional mammographic views or an ultrasound test.

"When we weigh the relative value of the benefits, namely saving lives, of implementing the new recommendations, versus the potential harms or risks, it comes out way in favor of starting annual mammography at age 40," Dr. Lee said. "We feel that you can't equate having a life saved with cost savings or reduction in unnecessary testing."

Another argument advanced by the ACR is that 75% of women in whom breast cancer develops are not considered at high risk and that screening only high-risk women would miss three quarters of breast cancers. As previously reported by Medscape Medical News , a study by R. Edward Hendrick, PhD, and Mark Helvie, MD, published in the February issue of the American Journal of Radiology, analyzed the same data as did the USPSTF, but with a vastly different conclusion.

They showed that if USPSTF guidelines for breast cancer screening were followed, as many as 100,000 women, now 30 to 39 years old and preparing to enter screening age, would ultimately die unnecessarily from breast cancer. Women who receive annual mammograms starting at age 40 years could significantly reduce breast cancer mortality risk by 71%, whereas women following the USPSTF guidelines would only have a 23.2% reduction in mortality risk.

"The barriers to widespread implementation of the ACOG recommendations are those facing delivery of health care in general, namely issues of costs, coverage, and access, which are nothing new," Dr. Lee said. "Depending on their community and their insurance coverage, some women may have to travel further or to wait longer to have their screening mammogram. But here we have a public health measure that works, and we should allocate health care dollars to screening mammography, and, if necessary, cut health care spending for measures that have not been shown to be as effective."

A recent survey presented at ACOG's 59th Annual Clinical Meeting indicated that women's attitudes, in part influenced by media coverage, may actually favor implementation of the ACOG vs the USPSTF guidelines.

"Since the widespread introduction of mammography screening, breast cancer mortality has decreased," Dr. Lee concluded. "This may not all be due to screening, but we know that tumors detected in early stages are associated with better survival."

Obstet Gynecol. 2011;118:372-382.


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