Healthy people with average cancer risk
Women over 45
The United States Preventative Services Task Force (USPSTF) recommends a screening mammogram every other year for women ages 50-74 who are at average risk for breast cancer. But do all patients in this category benefit from this screening regimen?
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Using personal breast cancer risk and breast density to determine the frequency of screening mammograms for women over age 50.
The widespread use of screening and treatment has resulted in fewer breast cancer deaths for women in the United States. But along with the benefits, some harms come from detection and early intervention.
This study uses computer models to suggest that breast cancer screening intervals can be tailored to each woman depending on her breast cancer risk and breast density. Researchers did not study actual patients who had screening every one, two or three years. Instead, they modeled and predicted what would happen if these women were to use these screening intervals. More work needs to be done to understand how we can tailor screening intervals for each patient. Currently, patients and their health care providers should work together to determine a patient’s optimal breast cancer screening interval based on her personal breast cancer risk factors.
The National Comprehensive Cancer Network (NCCN) establishes guidelines for breast cancer screening and cancer care in the U.S. For women with increased risk (a lifetime risk for breast cancer of 20% or more), the guidelines recommend the following screening:
With regards to dense breasts and screening, NCCN guidelines state the following:
Laws on breast density notification vary by state.
The following breast cancer screening clinical trials are currently enrolling participants:
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Cancer Therapy Advisor
The 2016 U.S. Preventive Services Task Force (USPSTF) made the controversial recommendation that women aged 50-74 should get screening mammograms every other year, rather than annually. However, do all women in this age group benefit from the same screening mammogram regime? Amy Trentham-Dietz and her colleagues from the University of Wisconsin Carbone Cancer Center and other institutions published work in the Annals of Internal Medicine that addresses this question.
Can a woman’s breast density and breast cancer risk be used to determine the optimal time between her screening mammograms?
Researchers from the Cancer Intervention and Surveillance Modeling Network and the Breast Cancer Surveillance Consortium used three well-established models (Models E, GE, and W) to predict the benefits and harms of screening mammograms for women 50 years and older with various combinations of breast cancer risk and breast densities. This model used data collected from 1975-2010 by the Surveillance, Epidemiology, and End Results (SEER) program. The women modeled were at average or moderate (not greater than four times increased risk) risk for breast cancer. Factors leading to a moderate risk of breast cancer included postmenopausal obesity, a history of benign breast biopsies, and a history of lobular carcinoma in situ (LCIS). Note that moderate breast cancer risk is not as great as the risk of women with BRCA mutations. Benefits measured were breast cancer deaths avoided due to screening, and quality-adjusted life-years. Harmful outcomes measured were false positive mammograms, benign biopsies, and overdiagnosis (defined as “screen-detected cancer that would not have been diagnosed in a woman's lifetime in the absence of mammography”).
Because this study only included information from women who were 50 years and older, the findings do not apply to younger women. Nor did it look at women who are at higher risk of breast cancer due to a genetic mutation such as BRCA that increases breast cancer risk. And finally, because these results are predicted from a computer model, it assumes that patients will adhere to the screening schedule, which may not be the case for all women.
The conclusions also hinge on how the authors define harm and whether patients would use the same definition. For some women, being called back for additional screening or having a benign biopsy may appear to be a harm. Other women may prefer to have this additional screening, despite the risk that a detected abnormality turns out to be something other than cancer. This points to a need for personalizing breast screening, not only based on a patient’s risk for breast cancer, but also on her preferences.
It is important to note that this paper used current USPSTF guidelines for breast cancer screening in average risk women as a starting point. These guidelines are controversial and differ from others. Guidelines of numerous other organizations, including the American Cancer Society (ACS), the National Comprehensive Cancer Network (NCCN), the American Medical Association (AMA), the American College of Radiology (ACR), and the American Congress of Obstetricians and Gynecologists (ACOG) recommend annual screening mammograms beginning at younger ages—the ACS recommends age 45, while the other organizations recommend age 40. Recently, the NCCN added that women and their doctors consider using 3D mammography (tomosynthesis), which is not addressed in this study.
Separate guidelines exist for women known to be at high risk for breast cancer due to mutations in BRCA or other genes associated with increased cancer risk, a strong family history of breast cancer, and/or history of radiation treatment to the chest. In some cases, guidelines recommend combining magnetic resonance imaging (MRI) with mammography. These types of screening were not addressed by this study.
This study suggests that a woman’s breast density and breast cancer risk can be used to tailor her breast cancer screening interval. These findings are not definitive, because they used computer models to predict the results of being screened at one-, two-, or three-year intervals. However, this research opens discussion on how to tailor screening to benefit each patient individually. Additionally, more work needs to be done to address the limitations of the study, including women who are younger and have mutations in genes that increase cancer risk.
While this study is a step towards personalizing breast cancer screening for women who do not have mutations in BRCA or other genes that increase cancer risk, more work is needed to correctly identify women who would benefit from increased screening. Patients and their health care providers should work together to determine a patients’ optimal screening regimen based on personal and family history of cancer, as well as the patient’s tolerance for the risk of false positives and/or benign biopsies.
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