Study: How do ultrasound and mammography compare in breast cancer screening?
|At a glance||Questions for your doctor|
What is this study about?
The study looks at the effectiveness of ultrasound as compared to mammography for breast cancer screening.
Why is this study important?
In general, the number of breast cancer cases worldwide is increasing. Women in developing countries do not have easy access to mammography, and some lack breast cancer screening entirely. Ultrasound has many advantages: it does not use ionizing radiation, the machinery is portable and not as expensive as mammography, making it a more viable alternative for women in developing countries.
- A total of 111 breast cancers were found in three years. (The study included a total of 7473 breast cancer screens in patients at increased risk for breast cancer.) Of these 111 breast cancers, 58 were found through ultrasound and 59 were found through mammography.
- There were more false positives among the patients who got ultrasounds compared to patients who got mammography. The recall rate for ultrasounds was about 11% while the recall rate for mammograms was about 9%.
What does this mean for me?
Ultrasound and mammography have similar cancer detection rates, although there are more false positives found through ultrasound. However, this finding does not mean that ultrasound should replace mammography. According to the study authors, “…these results suggest that screening [ultrasound] could be a viable alternative to mammography in countries lacking organized screening, particularly with availability of low-cost, portable [ultrasound] systems. Where mammography is available, [ultrasound] should be seen as a supplemental test for women with dense breasts who do not meet high-risk criteria for screening MRI and for high-risk women with dense breasts who are unable to tolerate MRI.” National guidelines recommend that women who have mutations in BRCA or other genes that increase their risk of breast cancer undergo increased surveillance for breast cancer using both MRI and mammography. It is important to remember that this study looked at women at high risk for breast cancer. The results may not apply to women with an average lifetime risk of breast cancer.
Berg WA, Bandos AI, Mendelson EB, et al. “Ultrasound as the Primary Screening Test for Breast Cancer: Analysis from ACRIN 6666.” Journal of the National Cancer Institute. Published online first on December 28, 2015.
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This article is relevant for:
Young women at high risk for breast cancer with limited access to mammography and MRI is not easily accessible
This article is also relevant for:
People with a genetic mutation linked to cancer risk
Women under 45
Women over 45
Be part of XRAY:
There are laws and guidelines for screening in women with dense breasts. The laws on breast density notification vary by state. The National Comprehensive Cancer Network (NCCN) has guidelines on breast screening. The panel notes that dense breasts are associated with an increased risk for breast cancer, and they recommend the following:
- Women with dense breasts on mammogram should be counseled on the risks and benefits of additional breast screening.
- Digital mammograms benefit young women and women with dense breasts.
- Tomosynthesis (3D mammograms) can increase cancer detection and lower the chances of additional call backs.
- Ultrasound may improve the detection of cancers in women with dense breasts but it can also increase the number of call backs and biopsies of benign (noncancerous) tissue.
- I carry a mutation in a gene that increases cancer risk. How does this change the breast cancer screenings I should receive?
- I have dense breasts—can I get ultrasounds in addition to mammograms?
- Will my health insurance cover breast MRI? If they do not cover it, are there financial assistance programs?
- I have difficulty accessing mammograms. Can I get ultrasounds instead?
- I have a medical reason why I cannot have MRI, should I get ultrasounds?
The following are breast cancer screening or prevention studies enrolling people at high risk for breast cancer.
- NCT04067726: Denosumab and Mammographic Density in Premenopausal Women With Dense Breasts (TRIDENT). This study is looking at the drug denosumab to learn if it can reduce breast density in high-risk premenopausal women who have dense breasts.
- The Risk Factor Analysis of Hereditary Breast and Ovarian Cancer In Women with BRCA1, BRCA2 or PALB2 Mutations This study seeks to improve researchers’ understanding of how hormonal, reproductive and lifestyle factors may be associated with cancer in this high-risk population.
Additional risk-management clinical trials for people at high risk for breast cancer may be found here.
Who covered this study?
Ultrasound may be useful supplemental test for breast cancer This article rates 5.0 out of 5 stars
Breast ultrasound, mammography may be equally effective: study This article rates 4.5 out of 5 stars
Study: Add ultrasound in cancer fight for some This article rates 4.0 out of 5 stars
IN DEPTH REVIEW OF RESEARCH
Previous work has shown that mammograms reduce the number of breast cancer deaths. In women from age 40-49, researchers have seen a 15% reduction in breast cancer deaths; a 22% reduction has been seen in women from age 50 -74. It is believed that older women benefit more from mammography because their breasts are not as dense as those of younger women. In addition to ultrasound’s portability and cost benefits, the quality of ultrasound images are not as limited by breast density as are mammography images.
In January 2016, Wendie Berg and colleagues at the Magee-Womens Hospital of University of Pittsburgh Medical Center and other institutions published a study in the Journal of the National Cancer Institute that compared all aspects of cancer detection from ultrasound and mammography.
What researchers of this study wanted to know:
Is ultrasound a viable alternative to mammography?
Population(s) looked at in the study:
This study included 2,662 women who did not have breast cancer, but did have dense breasts. These women also had to have one other risk factor for breast cancer (for example, a BRCA mutation, an atypical breast biopsy, or high risk scores through the Gail test for Breast Cancer Risk Assessment).
- One hundred and eleven breast cancers were found in a three- year period from a total of 7473 breast cancer screens in patients at increased risk for breast cancer. Of these 111 breast cancers, 58 were found through ultrasound and 59 were found through mammography.
- It took 129 ultrasound screens to detect 1 cancer.
- It took 127 mammogram screens to detect 1 cancer.
- 89 of the breast cancers were invasive. Of the 89 invasive cancers, 53 were found by ultrasound and 41 were found by mammography.
- Fifty-three of the 58 cancers found by ultrasound were invasive; the other five were ductal carcinoma in situ (DCIS). Forty-one of the 59 cancers found by mammogram were invasive; the other 18 were DCIS. These results indicate that ultrasound screening may be better able to identify invasive cancers.
- There were more false positives found in patients who got ultrasounds compared to patients who got mammograms. The recall rate for ultrasounds was about 11% while the recall rate for mammograms was about 9%.
- The biopsy rate for the women who got called back based on their ultrasound results was about 6% while it was 2% for women who got called back based on their mammogram results.
In order to participate in this study, women had to have dense breasts and at least one other risk factor for breast cancer, meaning that they were all at greater risk for breast cancer than women in the general population. Therefore, the results of this study may be more applicable to young breast cancer survivors. Had study participants been at average risk for breast cancer, the results may have been different. For now, the results apply only to women at high risk of breast cancer.
This study suggests that ultrasound may be a viable alternative to mammography for women in countries that do not have access to mammography. Ultrasound should not be a replacement, however, for women who can access mammography. The researchers saw that more invasive cancers were detected by ultrasound as compared to mammography; however, they write, “a larger study is needed to statistically support greater sensitivity of ultrasound to invasive cancers.”