Mammograms
MAMMOGRAM- SCREENING 4/07
ACP Guideline for Mammography Encourages Individual Decisions for Women 40 to 49 Years CME/CE
News Author: Laurie Barclay, MD
CME Author: Charles Vega, MD, FAAFP
April 2, 2007 — The American College of Physicians (ACP) recommends tailoring the decision about screening for breast cancer in women aged 40 to 49 years based on the woman’s concerns about mammography and breast cancer and her risk for breast cancer because of the associated benefits and risks for this age group. The new guidelines appear in the April 3 issue of the Annals of Internal Medicine, along with a background review article, an editorial, and a patient summary.
Available evidence suggests that breast cancer risk, and therefore the benefit of screening mammography, is not evenly distributed in women between the ages of 40 and 49 years. When weighing the possible benefits and harms of screening mammography, one must therefore consider individual risk for breast cancer, as well as susceptibility to and concerns regarding the harms of screening.
“We designed our screening mammography guideline based on scientific evidence,” Lynne Kirk, MD, FACP, president of the ACP, said in a news release. “It will empower women between the ages of 40 and 49 to become part of the decision-making process and to encourage them to discuss with their physicians the benefits and risks of mammograms…. If a woman between the ages of 40 and 49 decides not to have a mammogram, she and her doctor should re-address the issue every one to two years.”
Following a rigorous process based on extensive review of available scientific evidence, the ACP panel developed evidence-based guidelines rather than expert-opinion or consensus guidelines. In addition to articles reporting findings from the original mammography trials, the ACP panel reviewed 117 studies concerning the risks and benefits of mammography screening for women between the ages of 40 and 49 years.
The ACP panel concludes that evidence is insufficient to recommend for or against screening all women in this age group for breast cancer. The guidelines recommend that women discuss breast cancer screening with their primary care clinician and make the decision that best suits their specific risks and individual preferences.
“It is important to tailor the decision of screening mammography by discussing the benefits and risks with a woman, addressing her concerns, and making it a joint decision between her and her physician,” says lead author Amir Qaseem, MD, PhD, MHA, from the Medical Education and Publishing Division at ACP.
Among women in the United States, breast cancer is the second most frequent cause of cancer mortality, with 25% of all diagnosed cases occurring in women younger than 50 years. Risk for breast cancer in this age group varies considerably, from less than 1% for a 40-year-old woman with no risk factors to 6% for a 49-year-old woman with multiple risk factors such as family history of breast cancer, older age at the birth of first child, and younger age at menarche.
Despite good evidence that mammography reduces mortality from breast cancer in 50- to 70-year-old women, mandating routine screening for women in this age group, evidence in younger women is conflicting. A 2002 meta-analysis by the US Preventive Services Task Force reviewed data from many clinical trials and estimated that screening mammography every 1 to 2 years in women aged 40 to 49 years was associated with a 15% decrease in breast cancer mortality after 14 years of follow-up. However, a separate Canadian study showed no benefit from mammography for women in this age group.
Reflecting the disparity in these findings, the US Preventive Services Task Force and the American College of Obstetricians and Gynecologists both recommend screening mammography every 1 to 2 years for women in the 40- to 49-year-old age group, whereas the 2006 American Cancer Society guideline recommends yearly mammograms beginning at age 40 years.
The ACP guideline presents the available evidence for screening mammography to assist clinicians in counseling women between the ages of 40 and 49 about the benefits and risks of screening mammography within this age group. The primary benefit of screening mammography is decreased mortality from breast cancer, but the potential harms of screening mammography include false-positive results, possible unnecessary treatment of lesions that would not have become clinically significant, radiation exposure, and procedure-associated pain.
“There are important benefits to screening mammography, but we believe the decision to be screened should be based on an informed conversation between a patient and her physician,” says ACP Guideline Committee chair Douglas K. Owens, MD, MS, from the Veterans Affairs Palo Alto Health Care System and Stanford University School of Medicine in California. “In our view, the evidence doesn’t support a blanket recommendation for women in this age group.”
The ACP panel concluded that screening mammography for women between the ages of 40 and 49 years is likely to reduce mortality from breast cancer slightly, but, as with any screening procedure, it carries the burden of potential harms.
The ACP expert panel provided 4 main recommendations concerning screening mammography for women between the ages of 40 and 49 years:
- To help guide decisions about screening mammography, clinicians should periodically perform individualized assessments of risk for breast cancer.
- Clinicians should inform these women about the potential benefits and harms of screening mammography.
- Clinicians should make their decisions concerning screening mammography on a case-by-case basis, considering not only the benefits and harms of screening, but also the woman’s individual preferences and her specific breast cancer risk profile.
- Further research should be done on the net benefits and harms of breast cancer screening modalities for women in this age group.
Despite considerable variation in women’s beliefs concerning mammography or their own risks of developing breast cancer, the ACP panel suggests that the potential reduction in breast cancer mortality associated with screening will outweigh other considerations for many women.
“We still think many women will choose to get mammography, and we’re supportive of that,” Dr. Owens says. “The most important thing is that women be well-informed about the decision they’re making.”
The ACP funded the development of these guidelines.
In an accompanying editorial, Joann G. Elmore, MD, MPH, and John H. Choe, MD, MPH, from the University of Washington in Seattle, emphasize the need for clinicians to assist women in making informed decisions.
“Clinicians and patients must try to untangle the complex knot of social, political, and economic forces that influence decisions in breast cancer screening,” Drs. Elmore and Choe write. “We must listen carefully to our patients and communicate honestly the benefits and limitations of our imperfect tests.”
Ann Intern Med. 2007;146:511-515, 516-526, 529-532.
Clinical Context
Screening mammography for women younger than 50 years has been a controversial subject for some time. A systematic review of medical literature on this subject accompanies the current guidelines. In this review, Armstrong and colleagues evaluated 117 studies to quantify the benefits and risks of screening mammography for women between the ages of 40 and 49 years. They found that such testing reduces breast cancer mortality rates by 7% to 23%. In addition screening mammography increases the risk for mastectomy while decreasing the risks of receiving adjuvant chemotherapy and hormone therapy.
The rate of false-positive mammograms among women between the ages of 40 and 49 years is high, up to 56% after 10 mammograms. However, Armstrong and colleagues note that false-positive results did not significantly discourage women from receiving further mammograms.
Using this review as well as other research evidence, the ACP offers clinical guidelines for screening mammography among women between the ages of 40 and 49 years.
Study Highlights
- The decision of whether to perform screening mammography among women 40 to 49 years of age should be individualized for each patient. The 5-year risk of developing breast cancer at these ages can range from 0.4% to 6%. Women in this age range who have the following risk factors carry a higher risk for breast cancer vs women who are 50 years of age:
- 2 first-degree relatives with breast cancer
- 2 previous breast biopsies
- 1 first-degree relative with breast cancer plus 1 previous breast biopsy
- Previous diagnosis of breast cancer, atypical hyperplasia, or ductal carcinoma in situ
- Previous chest irradiation
- BRCA1 or BRCA2 mutation
- The risk assessment for breast cancer for each patient should be reevaluated every 1 to 2 years. Risk assessment tools, such as the Gail model, are limited in aiding clinicians and patients to make individualized decisions regarding screening mammography.
- Clinicians should inform patients of the potential benefits and harms of screening mammography, particularly the reduction in breast-cancer–associated mortality and high false-positive rates of screening.
- Regarding the benefits of breast cancer screening, the authors cite a recent meta-analysis in which the risk for mortality caused by breast cancer was reduced by 15% among women who received mammography between the ages of 40 and 49 years vs those who did not receive mammography. This risk reduction is lower than the 22% relative risk reduction in mortality caused by breast cancer associated with the use of mammography for women older than 50 years.
- Beside the risk for false-positive tests, pain is another negative factor weighing against the decision to perform screening mammography in younger women. Up to 77% of women report pain associated with the procedure. Other negative consequences of screening mammography include exposure to radiation and anxiety.
Pearls for Practice
- The current systematic review demonstrates that screening mammography among women between the ages of 40 and 49 years reduces breast cancer mortality and decreases the risk of receiving adjuvant chemotherapy. The rate of false-positive mammograms in this patient population is high, but false-positive tests do not necessarily discourage women from continuing screening mammography.
- The current ACP guidelines suggest that the decision of whether to perform screening mammography for women between the ages of 40 and 49 years should be individualized to account for the patient’s particular breast cancer risk factors, as well as the patient’s concerns about breast cancer and mammography. This decision should be revisited every 1 to 2 years during the fourth decade