Why is ultrasound screening for breast cancer lagging behind?

Supplemental breast cancer screening via ultrasound has many advantages compared to other modalities, but it has yet to reach its full potential, according to an opinion piece in the American Journal of Roentgenology.

Ellen B. Mendelson, MD, professor of radiology at Northwestern University Feinberg School of Medicine, and Wendie Berg, MD, PhD, professor of radiology at Magee-Womens Hospital of UPMC, wrote that there are several modalities that have potential as supplements to mammography, but all have various drawbacks.

Even though abbreviated screening MRI protocols are being developed that promise to reduce the cost and increase the availability of MRI screening, the authors pointed out that most women with dense breasts don’t meet the requirements for MRI screening under current guidelines. In addition, women with internal metal hardware (such as pacemakers) or who have claustrophobia aren’t candidates for the procedure.

An alternative such as digital breast tomosynthesis makes sense if it’s a primary screening exam, but if it’s a supplement to 2D full-field digital mammography it “is illogical to attempt to compensate for the limitations of one x-ray procedure by using another,” the authors wrote, particularly considering the additional amount of radiation a patient will be exposed to.

Ultrasound, on the other hand, isn’t associated with ionizing radiation, isn’t affected by breast density and doesn’t require IV contrast material. Despite these advantages, the acceptance of whole-breast ultrasound has “lagged,” Mendelson and Berg wrote. Why?

Possible explanations include the time and expertise needed to perform the exam. The exam is, after all, operator dependent. But these concerns “can be countered by a performer’s continuing medical education and personal experience stockpiled over time,” the authors wrote. Even automated ultrasound requires intensive training in performance and interpretation.

Mendelson and Berg pointed to the American College of Radiology Imaging Network (ACRIN) 6666 trial as an example of how rigorous ultrasound training programs can be put into place. For that trial, Investigators were required to have experience interpreting 500 breast ultrasound examinations in the previous two years and to complete weekend or equivalent training that included lectures on breast anatomy and physiology, mammographic and sonographic BI-RADS interpretation of masses and calcifications and the postsurgical breast.

“Ultrasound, which has been used in breast imaging for decades in diagnostic and interventional settings, is a newcomer to screening,” Mendelson and Berg concluded. “To realize ultrasound’s potential to increase the number of cancers detected, intensive training programs similar in scope to those designed for the investigators of ACRIN 6666 and focused on scanning the entire breast need to be put in place for physician performers, physician interpreters and technologist performers for both handheld and automated breast ultrasound systems."