WHEN TO BEGIN SCREENING WITH MAMMOGRAPHY?

November 16, 2009 ( UPDATED November 17, 2009 ) — The US Preventive Services Task Force (USPSTF) has issued new breast cancer screening guidelines, which are published in the November 17 issue of the Annals of Internal Medicine. The task force now recommends against routine mammography screening for women before age 50 years and suggests that screening end at age 74 years.

The new USPSTF recommendations are in opposition to other existing breast cancer screening guidelines from organizations such as the American Cancer Society and the American College of Radiology, which have both criticized the new document. Several agencies and organizations, such as the Seattle Cancer Care Alliance, have said they will continue to follow the American Cancer Society guidelines. However, according to an article in the New York Times, advocacy groups like the National Breast Cancer Coalition, Breast Cancer Action, and the National Women’s Health Network "welcomed the new guidelines."

Updated USPSTF Breast Cancer Screening Guidelines

The new USPSTF guidelines, which update those they issued in 2002, also recommend changing the screening interval from 1 year to 2 years and suggest that women aged 40 to 49 years who are at high risk for breast cancer consult with their clinician concerning the optimal time to begin regular, biennial screening mammography.

"Mammography, as well as physical examination of the breasts, can detect presymptomatic breast cancer," write Ned Calonge, MD, MPH, from the Colorado Department of Public Health and Environment in Denver, and colleagues from the USPSTF. "Because of its demonstrated effectiveness in randomized, controlled trials of screening, film mammography is the standard for detecting breast cancer; in 2002, the USPSTF found convincing evidence of its adequate sensitivity and specificity."

Because of insufficient evidence to determine the benefits and harms of screening mammography in women older than 75 years, the updated guidelines recommend stopping screening at age 74 years.

Because the USPSTF found adequate evidence that teaching self-examination is not associated with a decrease in breast cancer mortality rates, the task force recommends against teaching breast self-examination (BSE).

Current evidence is now insufficient to evaluate additional benefits and harms of clinical breast examination (CBE) for women aged at least 40 years. This recommendation is a change from the 2002 statement, which endorsed mammography screening, with or without CBE, annually or biennially for women 40 years or older.

Film mammography is associated with decreased breast cancer mortality rates, particularly in women aged 50 to 74 years, based on evidence to date. Women aged 60 to 69 years appear to have the greatest benefit, whereas evidence of benefit associated with film mammography is lacking for women aged at least 75 years.

Current evidence is insufficient to determine additional benefits and harms of either digital mammography or magnetic resonance imaging (MRI) as screening modalities for breast cancer vs film mammography. Therefore, the USPSTF did not recommend one form of mammography vs another.

The evidence base for the updated guidelines was a systematic review of published evidence of the efficacy of the 5 screening modalities in lowering breast cancer mortality rates. These include film mammography, CBE, BSE, digital mammography, and MRI.

Other evidence reviewed by the USPSTF included 2 studies commissioned by the task force. These were a systematic evidence review targeting 6 questions concerning the benefits and harms of screening and a decision analysis using population modeling techniques to determine anticipated health costs and outcome benefits of screening every year vs every 2 years, and of starting and ending mammography screening at various ages.

Specific Recommendations

Specific recommendations of the USPSTF, and the accompanying strength of recommendations, were as follows:

• The USPSTF recommends against routine screening mammography in women aged 40 to 49 years. Based on patient context, including patient values concerning specific benefits and harms, individual decisions should be made regarding starting regular, biennial screening mammography before age 50 years (grade C recommendation).
• Women aged 50 to 74 years should undergo biennial screening mammography (grade B recommendation).
• Current evidence is insufficient to determine additional benefits and harms of screening mammography in women 75 years or older (I statement).
• In women 40 years or older, current evidence is insufficient to determine the additional benefits and harms of CBE beyond screening mammography (I statement).
• The USPSTF recommends against clinicians teaching women the technique of BSE (grade D recommendation).
• Current evidence is insufficient to determine additional benefits and harms of either digital mammography or MRI vs film mammography as screening modalities for breast cancer (I statement).

Evidence-Based Findings

The accompanying updated evidence review on breast cancer screening looked at published studies identified from a search of Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews through the fourth quarter of 2008, MEDLINE January 2001 to December 2008, and bibliographies of identified articles. Also reviewed were Web of Science searches and Breast Cancer Surveillance Consortium for screening mammography data.

"Mammography screening reduces breast cancer mortality for women aged 39 to 69 years; data are insufficient for older women," write Heidi D. Nelson, MD, MPH, from Oregon Health & Science University in Portland, and colleagues. "False-positive mammography results and additional imaging are common. No benefit has been shown for CBE or BSE."

Inclusion criteria for studies were randomized controlled trials with breast cancer mortality outcomes for screening effectiveness and studies of varying designs and multiple data sources regarding harms. The reviewers found that for women aged 39 to 49 years, mammography screening was associated with a 15% decrease in breast cancer mortality rates (relative risk, 0.85; 95% credible interval, 0.75 - 0.96; 8 trials). However, data are lacking for women 70 years or older.

Radiation exposure from mammography is low, and adverse experiences are common but transient and do not alter screening practices. The estimated rate of overdiagnosis from screening ranges from 1% to 10%. Compared with older women, younger women have more false-positive mammography results and additional imaging but fewer biopsies. Trials of CBE are ongoing. In trials of BSE, benign biopsy results increased, and there were no decreases in mortality rates.

Study Limitations

Limitations of this review include lack of studies in older women, lack of digital mammography studies, and lack of MRI studies.

"We can improve primary and secondary breast cancer prevention effectiveness by implementing risk assessment in primary care and mammography facilities and providing tailored recommendations for prevention based on individual risk," Karla Kerlikowske, MD, from San Francisco Veterans Affairs Medical Center in San Francisco, California, writes in an accompanying editorial.

"Health professionals will need education about how to communicate breast cancer risk to women, potential benefits and harms of prevention interventions, and how to assist women in understanding which factors might influence their choice to have an intervention or not. Women should have the opportunity to make informed choices about primary and secondary breast cancer prevention on the basis of their risk for disease and the potential benefits and harms of prevention interventions."

The guidelines were supported in part by a National Cancer Institute–funded Breast Cancer Surveillance Consortium cooperative agreement and National Cancer Institute–funded University of California, San Francisco, Breast Cancer Specialized Programs of Research Excellence.

The updated evidence review was supported by grants from the Oregon Evidence–based Practice Center under contract to the Agency for Healthcare Research and Quality, the Veterans Administration Women's Health Fellowship, and the Oregon Health & Science University Department of Surgery in conjunction with the Human Investigators Program.

The USPSTF is an independent, voluntary body supported by the Agency for Healthcare Research and Quality. Recommendations made by the USPSTF are independent of the US government and should not be construed as an official position of the Agency for Healthcare Research and Quality or the US Department of Health and Human Services.

The review authors, task force, and editorialist have disclosed no relevant financial relationships.

Ann Intern Med. 2009;151:716-726, 727-737, 750-752.