Ultrasound Detects Earlier, More-Aggressive Cancers
in Dense Breasts
Rachel F. Brem
Preliminary data from a study published in the February 2015 issue of AJR suggest that bilateral handheld screening ultrasound can detect early-stage mammographically occult breast cancers in patients with dense breast tissue.
Coauthor Rachel F. Brem talked with Insight about the findings.
How do ultrasound findings differ from those of mammography?
The sensitivity of mammography is 85%, which decreases to 65% in women with dense breast tissue. Unlike mammography, where both breast tissue and breast cancer present as a white density, breast tissue is hyperechoic or white and breast cancer is hypoechoic with ultrasound; therefore, the detection of breast cancer in women with dense breast tissue is compromised with mammography, but optimized with ultrasound.
What are the benefits of screening dense breasts using ultrasound technology?
Women with dense breast tissue have both a lower sensitivity for cancer detection with mammography and an increased risk of breast cancer. Increased breast density is an independent risk factor for developing breast cancer; therefore, adjunct imaging modalities to detect mammographically occult breast cancer are needed to improve breast cancer detection.
Several imaging modalities have been shown to detect mammographically occult breast cancer, including MRI, breast-specific gamma imaging (BSGI), and ultrasound. In addition to being the most cost effective of these modalities, ultrasound does not require an injection and does not expose the patient to radiation.
Although other modalities have higher sensitivity than mammography, screening breast ultrasound is the most appropriate modality to integrate into the screening environment. The additional breast cancers detected by ultrasound are largely invasive, small, and node negative. They are clinically significant, early-stage cancers whose detection may affect breast cancer mortality.
Acknowledgement of the need to inform women of the risk and diagnostic limitations of having dense breast tissue has gained momentum: Twenty states now have laws mandating that women be informed that they have dense tissue and that additional imaging modalities can detect additional cancers.
The article describes the findings of several studies of technologies for screening dense breasts. Did you find a common theme in the results?
All of the studies of hand-held or automated screening breast ultrasound revealed an additional two to four breast cancers in women with dense breast tissue. When detected in women with normal mammograms, these cancers are largely invasive, node-negative cancers. Therefore, the uniformity of the results confirms the value of detecting additional, clinically important cancer in women with dense breast tissue whose screening mammograms are normal.
What are some of the workflow implications of using ultrasound to screen dense breasts?
Hand-held screening ultrasound is effective in detecting additional cancers. However, studies have shown that it is a time-consuming effort, with up to 20 minutes of scanning time. Although in some practices the radiologist scans the patient, in other practices a trained technologist scans the patient and presents the radiologist with representative images of identified abnormalities. Optimally, the radiologist would interpret the entire study. This is best facilitated when the scanning and the image review are uncoupled, as occurs with automated breast ultrasound. The entire study is captured and reviewed by the radiologist via reconstruction software.
What should our readers—practicing radiologists—take away from the article?
Screening for breast cancer should take a risk-based approach. For women without other risk factors who do not have dense breast tissue, mammography is likely sufficient for screening. For women at substantially increased risk (greater than 20% lifetime risk of breast cancer), screening with MRI or BSGI should be considered, as they have the highest sensitivity. However, for women with intermediate risk— (15–20% lifetime risk of breast cancer) screening breast ultrasound, whether hand-held or automated, can detect additional breast cancers.