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The Latest Word on Screening Mammography for Younger Women
Abstract & Commentary
By Eileen C. West, MD, Director of Internal Medicine Women's Health, Clinical Assistant Professor of Internal Medicine, University of Oklahoma School of Medicine, Oklahoma City, Oklahoma. Dr. West reports no financial relationship to this field of study.
Synopsis: New guidelines from the ACP suggest that rather than universal screening, women aged 40-49 should be assessed for individual risk of breast cancer, and should be informed of the potential benefits and harms of screening mammography, then selectively screened based on the findings.
Source: Qaseem A, et al. Screening Mammography for Women 40-49 years of Age: A Clinical Practice Guideline from the American College of Physicians. Ann Int Med. 2007;146:511-515.
Breast cancer is the second leading cause of cancer related death among women in the U.S. More than 40,000 die of the disease yearly.1 Screening mammography reduces breast cancer mortality in women 50-70 years of age. Though 25% of all diagnosed cases are among women younger than 50 years of age, screening mammography in this age group has been the subject of intense debate. The USPSTF performed a meta-analysis recently which concluded that mammography every 1-2 years in women 40-49 resulted in a 15% decline the breast cancer mortality rate after 14 years, but the data varied widely with a large confidence interval, suggesting that the reduction could be as much as 27% or as little as 1%.2 Because risks are associated with screening, the authors of this new position statement report that risks, benefits and patient preferences ought to be the basis of screening, not age alone.
The group makes four specific recommendations:
Recommendation 1: In women 40-49 years of age, clinicians should perform individualized assessment of risk for breast cancer to help guide decisions about screening mammography. This assessment should be updated every 1-2 years. In this age group, women with any of the following risk factors have a higher risk than the average 50 year old woman: 2 first-degree relatives with breast cancer; 2 previous breast biopsies; 1 first-degree relative and 1 previous breast biopsy; previous diagnosis of breast cancer, DCIS, or atypical hyperplasia; previous chest irradiation or BRCA1 or BRCA2 mutation. More detailed family history patterns are found in the article, and include both sides of the family.
Recommendation 2: Clinicians should inform women 40 to 49 years of age about the potential benefits and harms of screening mammography. The primary benefit, of course, is early detection of breast cancer. The harms include biopsies, surgery, radiation exposure, false-positive results, and false reassurance, as well as procedure-associated pain and increased anxiety. The rate of false positives have been reported to range anywhere from 1% to 6.5%, and one study showed a cumulative rate of false-positive mammograms of 38% after 10 years of screening.3 Another issue is the increased diagnosis of ductal carcinoma in situ (DCIS). The natural history of DCIS is unknown, as is the percentage of these tumors that will progress to more serious disease. DCIS is treated with mastectomy (33%), lumpectomy (64%) and/or radiation (52%). Although not all cases require aggressive treatment, reliable predictors of biological aggressiveness have not been successfully outlined.
Recommendation 3: Clinicians should base screening mammography decisions on benefits and harms of screening, as well as on a woman's preferences and breast cancer risk profile. Women will vary in their desire to start screening in the 40-49 year old age group. For those who don't wish to discuss the screening decision, screening mammography every 1-2 years is reasonable.
Recommendation 4: The group's final recommendation was for further research.
The latest screening recommendations join a long list of recommendations from other organizations, such as the Canadian Task Force of Preventive Health Care (2001), The USPSTF (2002), and the American College of Obstetrics and Gynecology (2003). These organizations reached general consensus on screening every 1-2 years with or without clinical breast exam. The American Cancer Society (2006), which favors more aggressive screening in general, recommends a yearly mammogram starting at age 40 and continuing for as long as a woman is in good health.
The biggest change with the latest guideline is the allowance for "wiggle room" for those women with few risk factors to wait a while on screening. They acknowledge that many will still choose to be screened, but believe that screening in this age group, based on existing data, is best addressed with more individualized treatment and education of the patient. They want physicians to query patients regularly on risk factors, and make patients aware that the tests, while inexpensive and easy to perform, are not without harm.
Once again we find that discussion time in the exam room saves money on testing. However, many clinicians may not take the time for this discussion, since talk isn't reimbursed well and busy schedules demand time be placed on more pressing issues. Also, the legal issues have not been addressed when screening tests are not ordered. The academic exercise has merit, however, and can be accomplished without substantial increase in time if a questionnaire is given to the patient to be filled out ahead of time outlining her risk factors. The physician can then explain, if the patient is considered low risk, that the choice is hers to have a mammogram or wait another year and reconsider.
1. American Cancer Society. Cancer Facts & Figures 2005. Atlanta: American Cancer Soc; 2005.
2. Humphrey LL, et al. Ann Intern Med. 2002;137:347-360.
3. Olivotto IA, et al. N Engl J Med. 1998:339-560.