Recommendation 1: In women 40 to 49 years of age, clinicians should periodically perform individualized assessment of risk for breast cancer to help guide decisions about screening mammography.
A careful assessment of a woman's risk for breast cancer is important. The 5-year breast cancer risk can vary from 0.4% for a woman age 40 years with no risk factors to 6.0% for a woman age 49 years with several risk factors. Factors that increase the risk for breast cancer include older age, family history of breast cancer, older age at the time of first birth, younger age at menarche, and history of breast biopsy. Women 40 to 49 years of age who have any of the following risk factors have a higher risk for breast cancer than the average 50-year-old woman: 2 first-degree relatives with breast cancer; 2 previous breast biopsies; 1 first-degree relative with breast cancer and 1 previous breast biopsy; previous diagnosis of breast cancer, ductal carcinoma in situ (DCIS), or atypical hyperplasia; previous chest irradiation; or BRCA1 or BRCA2 mutation. A family history can also help identify women who may have BRCA mutations that place them at substantially higher risk for breast and other types of cancer (see Table below). These women should be referred for counseling and recommendations specific to this population, as recommended by the U.S. Preventive Services Task Force (USPSTF) (see the National Guideline Clearinghouse summary of the USPSTF guideline Genetic risk assessment and BRCA mutation testing for breast and ovarian cancer susceptibility: recommendation statement). Risk assessments should be updated periodically, particularly in women whose family history changes (for example, a relative receives a diagnosis of breast or ovarian cancer) and in women who choose not to have regular screening mammography. Although no evidence supports specific intervals, we encourage clinicians to update the woman's risk assessment every 1 to 2 years.
Table. Family History Patterns Associated with an Increased Risk for BRCA1 or BRCA2 Gene Mutations*
Both maternal and paternal family histories are important
Women not of Ashkenazi Jewish heritage
Women of Ashkenazi Jewish heritage
- Two first-degree relatives with breast cancer, 1 of whom received the diagnosis at age <50 years
- A combination of >3 first- or second-degree relatives with breast cancer regardless of age at diagnosis
- A combination both breast and ovarian cancer among first- and second-degree relatives
- A first-degree relative with bilateral breast cancer
- A combination of >2 first- or second-degree relatives with ovarian cancer regardless of age at diagnosis
- A first- or second-degree relative with breast and ovarian cancer at any age
- A history of breast cancer in a male relative
Any first-degree relative (or 2 second-degree relatives on the same side of the family) with breast or ovarian cancer
*Adapted from data from the U.S. Preventive Task Force (Genetic risk assessment and BRCA mutation testing for breast and ovarian cancer susceptibility: recommendation statement. Ann Intern Med. 2005;143: 355-61).
The risk for invasive breast cancer can be estimated quantitatively by using the Web site calculator provided by the National Institutes of Health (http://bcra.nci.nih.gov/brc/q1.htm). This calculator is based on the Gail model, which takes into account
many of the risk factors previously mentioned. However, clinicians who use the Gail model should be aware of its limitations. Although the model accurately predicts the risk for cancer for groups of women, its ability to discriminate between higher and lower risk for an individual woman is limited. This limitation occurs because many women have similar, relatively low absolute risks for invasive breast cancer over 5 years, which makes discrimination among levels of risk difficult for an individual woman.
Recommendation 2: Clinicians should inform women 40 to 49 years of age about the potential benefits and harms of screening mammography.
Screening mammography for women 40 to 49 years of age is associated with both benefits and potential harms. The most important benefit of screening mammography every 1 to 2 years in women 40 to 49 years of age is a potential decrease in breast cancer mortality. A recent meta-analysis estimated the relative reduction in the breast cancer mortality rate to be 15% after 14 years of follow-up (relative risk, 0.85 [95% credible interval, 0.73 to 0.99]). An additional large randomized clinical trial of screening mammography in women 40 to 49 years of age found a similar decrease in the risk for death due to breast cancer, although the decrease did not reach statistical significance (relative risk, 0.83 [95% confidence interval, 0.66 to 1.04]). Potential risks of mammography include false-positive results, diagnosis and treatment for cancer that would not have become clinically evident during the patient's lifetime, radiation exposure, false reassurance, and procedure-associated pain. False-positive mammography can lead to increased anxiety and to feelings of increased susceptibility to breast cancer, but most studies found that anxiety resolved quickly after the evaluation.
Recommendation 3: For women 40 to 49 years of age, 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.
Because the evidence shows variation in risk for breast cancer and benefits and harms of screening mammography based on an individual woman's risk profile, a personalized screening strategy based on a discussion of the benefits and potential harms of screening and an understanding of a woman's preferences will help identify those who will most benefit from screening mammography. For many women, the potential reduction in breast cancer mortality rate associated with screening mammography will outweigh other considerations. For women who do not wish to discuss the screening decision, screening mammography every 1 to 2 years in women 40 to 49 years of age is reasonable.
Important factors in the decision to undergo screening mammography are women's preferences for screening and the associated outcomes. Concerns about risks for breast cancer or its effect on quality of life will vary greatly among women. Some women may also be particularly concerned about the potential harms of screening mammography, such as false-positive mammograms and the resulting diagnostic work-up. When feasible, clinicians should explore women's concerns about breast cancer and screening mammography to help guide decision making about mammography.
The relative balance of benefits and harms depends on women's concerns and preferences and on their risk for breast cancer. Clinicians should help women to judge the balance of benefits and harms from screening mammography. Women who are at greater-than-average absolute risk for breast cancer and who are concerned that breast cancer would have a severely adverse effect on quality of life may derive a greater-than-average benefit from screening mammography. Women who are at substantially lower-than-average risk for breast cancer or who are concerned about potential risks of mammography may derive a less-than-average benefit from screening mammography.
If a woman decides to forgo mammography, clinicians should readdress the decision to have screening every 1 to 2 years.
Recommendation 4: We recommend further research on the net benefits and harms of breast cancer screening modalities for women 40 to 49 years of age.
Methodological issues associated with existing breast cancer screening trials, such as compliance with screening, lack of statistical power, and inadequate information about inclusion or exclusion criteria and study population, heighten the need for high-quality trials to confirm the effectiveness of screening mammography in women in this age group. Furthermore, harms of screening in this age group, such as pain, radiation exposure, and adverse outcomes related to false-positive results, should also be studied.