Breast cancer screening practices are a critical part of breast cancer detection. Laws around screening and notification of patients vary among states, but since 2009, more than 30 states have passed some form of legislation around notifying women of their breast tissue density. Some laws require that the notifications outline what supplemental testing options are available, such as ultrasound or MRI, and what the benefits of such exams might be.1
Study Provides Unique Insight on Detection
A recent study in the American Journal of Public Health suggests that notification of additional exam options for women with dense breast tissue may increase detection rates for breast cancer. That said, this held true only if the notification included the possible benefits of these supplemental exams, the authors found. Simply notifying women that their breast tissue was dense had no effect on the rate of cancer detection or the use of breast ultrasound.1
This new research highlights the role that ultrasound exam can play in breast cancer detection. There has been some debate about whether women with dense breast tissue should undergo supplemental breast ultrasound for cancer detection, but traditional 2D screening mammography doesn’t catch all cancers in dense breasts, according to the study authors. And up to 50 percent of women in the United States in their 40s and 50s have dense breast tissue.1
The study was new in that it looked at not only whether women used supplemental ultrasound after breast density notification laws were passed, but whether those supplemental exams resulted in detection of breast cancer that otherwise would have been missed. It found that they did. The use of supplemental MRI as well as ultrasound and biopsy increased in those states that required notification of breast density and the availability of supplemental exam options.1
The Role of Breast Ultrasound
Whole breast ultrasound is becoming more widely used as a supplemental exam option in addition to mammography, according to a recent review in Seminars in Ultrasound CT and MRI. Detection of cancer with mammography is imperfect, particularly in dense breast tissue, which may obscure an underlying tumor. Women with dense breast tissue have a four- to six-fold increase in their risk for breast cancer compared to women with mostly fatty breast tissue.2
Ultrasound is “a popular choice” among women according to the study authors “because it is well tolerated by patients, widely available, does not require intravenous contrast or ionizing radiation, and is relatively inexpensive.” However, it requires technologists or physicians with a high level of experience, and it has low specificity compared to mammography. For dense breast tissue, however, the authors find that whole breast ultrasound tends to perform better than mammography, with better sensitivity. They also found that ultrasound may detect more invasive cancers compared to mammography, an effect that applies even more to dense breast tissue: “it tends to detect more small node negative invasive cancers obscured by overlapping tissue on mammography,” they write.2
Despite ultrasound’s positive attributes, it is not a primary screening tool, but its role in breast cancer care has been growing steadily. Ultrasound does have limited ability to detect calcifications, and it is highly operator dependent. But false positives can be reduced with experience and careful criteria. As more practices begin to offer supplemental ultrasound exams, the experience of technologists will grow, and false positives will decline. As more states require that women with dense breast tissue are notified of their status and their options for additional exams, the use of supplemental ultrasound will continue to grow. Providers and patients alike should be aware of the options for screening and the benefits and possible harms of each type of supplemental exams.2
- Association of State Dense Breast Notification Laws With Supplemental Testing and Cancer Detection After Screening Mammography. American Journal of Public Health. https://ajph.aphapublications.org/doi/10.2105/AJPH.2019.304967 Last Accessed October 23, 2019.
- The Role of Ultrasound in Breast Cancer Screening: The Case for and Against Ultrasound. Seminars in Ultrasound CT and MRI. https://www.ncbi.nlm.nih.gov/pubmed/29317037 Last Accessed October 23, 2019.