As demonstrated by randomized clinical trials, mammographic screening provides a mortality benefit for women diagnosed with breast cancer. In addition, these cancers are not as expensive to treat with less invasive surgery and minimal chemotherapy. The benefits result because the cancer is detected at an earlier stage compared to tumours that are diagnosed when they become symptomatic. However, digital mammography is not infallible and breast cancers can be missed during screening, particularly if women have dense breast tissue. A false negative diagnosis can have devastating consequences, both in terms of treatment outcome and costs.
Seeking to address this problem, Ian Grady and colleagues from California have just published a study in Academic Radiology that aimed to determine the optimal screening strategy. Their paper is entitled: “The addition of automated breast ultrasound to mammography in breast cancer screening decreases stage at diagnosis.” This was a retrospective review of 3,454 women who had increased breast density (BI-RADS c or d) or an elevated risk of breast cancer. Most women were screened with full-field digital mammography (FFDM) followed by supplemental automated breast ultrasound (ABUS), although 5% opted for ABUS only. This resulted in the diagnosis of 122 cases of cancer.
The number of cancers seen on FFDM only was 39, the number detected by ABUS only was 42, while 41 breast cancers were seen on both modalities. The clinical example shown at left (© Association of University Radiologists) is an ABUS coronal view of a 6-mm invasive ductal carcinoma found in a 72-year-old woman where her FFDM image showed increased density but no suspicious findings. The yellow dot marks the nipple while the cross-hairs indicate the location of the tumour which is surrounded by architectural distortion and radial lines.
The authors stratified their findings according to the stage of the cancer at diagnosis and demonstrated that a combination of FFDM plus ABUS screening reduced advanced cancers by 40%. Compared to FFDM only, FFDM plus ABUS reduced advanced-stage cancers by 6% for all stages and by 11% for invasive cancers. They concluded: “For women with increased breast density or who are at high risk of developing breast cancer, a combination of screening mammography and whole-breast automated ultrasound is superior to mammographic screening. Screening ultrasound alone is also an effective screening strategy.”
CapeRay’s dual-modality Aceso system, which enables FFDM and ABUS images to be acquired simultaneously, has been explicitly developed to take advantage of the two different imaging modalities. As the title of this blog suggests, the evidence is mounting.