Mammography false negative rates rising, driven by a few key factors
Breast imaging false negative rates are rising across the U.S., driven by a few key factors, according to new research published Wednesday.
The number of women who had a screening mammogram miss cancer leapt from less than 1 per 1,000 women in 2010 up to as high as 2.5 by 2022. Such false negatives were much more likely to occur in patients with dense breasts, a personal or family history of cancer, and when an academic hospital delivered the mammogram.
These findings, published in the Journal of the American Journal of Roentgenology, give clues around how to improve imaging care, researchers charge.
“Exploration of the causes of the observed associations could inform quality assurance efforts to reduce the risk of delayed breast cancer diagnoses,” radiologist and lead author Eniola T. Oluyemi, MD, MPH, with Johns Hopkins Hospital in Baltimore, and colleagues wrote Oct. 22.
For the study, researchers analyzed information from the National Mammography Database, maintained by the American College of Radiology. Their sample included a total of over 38 million mammograms delivered to nearly 16 million women, including 32 million that were regular cancer screenings. Another 6 million were diagnostic exams, typically performed when there are signs of breast cancer, symptoms or other abnormalities. Among these diagnostic exams, the rate of women whose mammogram missed cancer climbed from as low as 2.3 per 1,000 in 2010 up to 5.4 by 2020, the study’s authors reported.
False negatives in the study encompassed all new cancer diagnoses within one year after a negative screening or diagnostic mammogram. These represented a combo of cancers that were hidden or undetectable, abnormalities missed by a radiologist on an earlier interpretation, and cancers that developed since the last breast exam. Oluyemi and co-authors said the rise in mammography misses has several potential explanations.
“A possible driver of increasing [false negative] rates could be the growing adoption of supplemental breast screening by breast MRI or ultrasound,” researchers wrote. “MRI is the most sensitive imaging modality for breast cancer, and breast ultrasound has greater sensitivity than mammography for the detection of invasive lobular breast cancer, which is often mammographically occult [i.e., hidden]. Additionally, women undergoing supplemental screening with breast MRI commonly alternate mammography and MRI every 6 months, providing time for a mammographically occult cancer to grow before the supplemental screening examination."
Race also showed a significant association with mammography misses, the authors added. For instance, false negatives were less likely in screening exams delivered to American Indian, Alaskan native, Asian, black and Hawaiian women, along with those of mixed race, compared to white women. Meanwhile for follow-up diagnostic mammograms, false negatives were less likely in Asian and Hawaiian patients and more likely in black or mixed-race women compared to their white counterparts. These differences may relate to variations in access to supplemental screening, insurance coverage challenges and out-of-pocket costs, which impact use of MRI and other modalities, often at sites historically serving the disadvantaged.
“Patients from underserved populations may lack access not only to insurance coverage but also to a primary care physician,” the authors wrote. “Such lack of access could prevent patients from receiving age-appropriate breast cancer screening itself, from undergoing cancer risk assessments to determine if supplemental screening is indicated, or from bringing a concerning breast symptom to a physician’s attention. Future research is needed to clarify the underlying causes of the observed associations of patient race with [false negative] rates, including the role of access to supplemental breast imaging tools.”
Read much more in the official journal of the American Roentgen Ray Society. Besides Hopkins, others participating in the study included ACR, Duke University, Durham, N.C., Washington University, St. Louis, Mo., Stanford Medicine, Stanford, Calif., the University of Pittsburgh and the State University of New York at Stony Brook, N.Y.
Marty Stempniak has covered healthcare since 2012, with his byline appearing in the American Hospital Association's member magazine, Modern Healthcare and McKnight's. Prior to that, he wrote about village government and local business for his hometown newspaper in Oak Park, Illinois. He won a Peter Lisagor and Gold EXCEL awards in 2017 for his coverage of the opioid epidemic.