Ultrasound Screening for Breast Cancer May Be Linked to Increased Detection of Invasive Tumors but More False-Positive Results
As reported in the Journal of the National Cancer Institute by Berg et al, an analysis from the American College of Radiology Imaging Network (ACRIN) 6666 study indicates that use of ultrasound in primary screening for breast cancer resulted in increased detection of invasive cancers but more false-positives vs mammography.
Study Details
In the study, 2,662 participants from 20 sites in the United States, Canada, and Argentina completed three annual screens (7,473 examinations) with ultrasound and film-screen (n = 4,351) or digital (n = 3,122) mammography and had biopsy or 12-month follow-up. At first screen, 93% of women identified themselves as white; 10%, as Hispanic; 3.4%, as African American; and 3.4%, as Asian.
Cancers Detected
Overall, there were 111 breast cancer events in 110 women. Of them, 89 (80.2%) were invasive cancers (median size = 12 mm); 57 (81%) with nodal staging were node-negative. The number of screens to detect 1 cancer was 129 (95% bootstrap confidence interval [CI] = 110–156) for ultrasound and 127 (95% CI = 109–152) for mammography. Cancer was detected by ultrasound in 58 cases (52.3%) and by mammography in 59 cases (53.2%; P = .90).
Ultrasound-detected cancers more likely (P < .001) to be invasive (53 of 58 = 91.4%; median size = 12 mm, range = 2–40 mm) vs mammography-detected cases (41 of 59 = 69.5%; median size = 13 mm, range = 1–55 mm). Invasive cancers detected by ultrasound were more frequently node-negative (34 of 53 = 64.2% vs 18 of 41 = 43.9%; P = .003).
Recall and Biopsy
For 2,659 first study screens, 98% of which were incidence screens for mammography (a prior screening mammogram was available) and approximately 11% of which were incidence screens for ultrasound, recall rates were 20.9% for ultrasound vs 11.5% for mammography (P < .001). For 4,814 incidence screens in years 2 and 3, for ultrasound vs mammography, recall rates were 10.7% vs 9.4% (P = .03), biopsy rates were 5.5% vs 2.0% (P < .001), and biopsy positive predictive value was 11.7% vs 38.1% (P < .001).
The investigators concluded: “Cancer detection rate with ultrasound is comparable with mammography, with a greater proportion of invasive and node-negative cancers among ultrasound detections. False positives are more common with ultrasound screening.”
The Avon Foundation for Women and the National Cancer Institute funded this study.
Wendie A. Berg, MD, PhD, of Magee-Womens Hospital, University of Pittsburgh School of Medicine, is the corresponding author of the Journal of the National Cancer Institute article.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
