By Will Boggs MD
NEW YORK (Reuters Health) - 21/3/2019
Rates of breast-cancer detection are similar after screening mammography with or without screening ultrasonography, according to an observational study.
Several states have mandated insurance coverage for screening ultrasonography in women with dense breasts, but the effect of supplemental screening on breast cancer outcomes remains unclear.
Dr. Janie M. Lee from Seattle Cancer Care Alliance and colleagues used data from the Vermont Breast Cancer Surveillance System and San Francisco Mammography Registry to assess the effect of screening ultrasonography as an adjunct to screening mammography versus screening mammography alone.
The study included more than 6,000 mammography-plus-ultrasonography exams in 3,386 women and more than 30,000 mammography exams alone in 15,176 matched women.
Although women receiving ultrasonography were more likely to have dense breasts than were those receiving mammography only, 25.7% of the former did not have dense breasts.
Women who also underwent ultrasonography were less likely than women who underwent mammography alone to need a second visit to complete diagnostic evaluations. But the addition of ultrasonography was associated with a significant jump in biopsy recommendations (from 27.7 to 57.4 per 1,000 screens).
Mammography plus ultrasonography was also associated with significant increases in short-interval follow-up for probably benign findings (3.9% vs. 1.1%) and false-positive biopsy recommendations (52.0 vs. 22.2 per 1,000 screens), as well as a significant decrease of the positive predictive value of biopsy recommendations (9.5% vs. 21.4%).
The cancer-detection rate did not differ significantly between mammography plus ultrasonography (5.4 per 1,000 screens) and mammography alone (5.5 per 1,000 screens), the researchers report in JAMA Internal Medicine, online March 18.
Most breast cancers were invasive ductal carcinomas, small (20 mm or smaller), node negative and positive for estrogen receptors and progesterone receptors, regardless of screening strategy.
"Our observational cohort study of ultrasonography screening in women across a range of breast cancer risk found modest, nonsignificant benefits and rates of screening harms that were high and consistent with prior reports," the researchers conclude. "To apply supplemental ultrasonography screening with greater effectiveness, we suggest that additional efforts are needed to more accurately identify women who will benefit from supplemental screening."
"We also suggest that development is required of the capacity to deliver high-quality supplemental screening, as well as new interventions to reduce the frequency of screening-related harms," they add.
Dr. Bonnie N. Joe of the University of California, San Francisco, who has studied various screening and imaging modalities for breast cancer, told Reuters Health by email, "Finding no significant difference in cancer-detection rate with use of supplemental screening ultrasound versus mammography alone was a surprise, as previous studies have shown a benefit of incremental cancer detection with screening ultrasound. As the authors mentioned in their discussion, this may relate to a combination of factors, including a sizable portion of average-risk women in the screened population and also variability in expertise and type of ultrasound screening used, such as hand-held versus automated, in the community setting."
"There is not yet sufficient data to make firm recommendations regarding which women with dense breasts should undergo supplemental screening and with what imaging test," said Dr. Joe, who was not involved in the study. "Ultrasound has traditionally been recommended because it is so well tolerated by women but the high rate of false positives is a recognized problem. If a woman has dense breasts and has a personal history of breast cancer or is otherwise at high risk for developing breast cancer, then supplemental screening with breast MRI is recommended as per American College of Radiology guidelines."
Dr. Lee did not respond to a request for comments.
JAMA Intern Med 2019.