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Addition of ultrasound to mammography improves breast cancer detection
The addition of ultrasound to a standard mammography appeared to increase sensitivity and detection of early breast cancers, according to results of a randomized controlled trial conducted in Japan.
Breast cancer incidence rates have been increasing in Japan and other Asian countries, where breast cancer tends to present at an earlier age compared with other developed nations, according to study background. Further, because Asian women tend to have denser breast tissue, standard screening based on U.S. and European practices may miss more cases of breast cancer in Asia.
Noriaki Ohuchi, MD, PhD, professor at Tohoku University Graduate School of Medicine in Miyagi, Japan, and colleagues evaluated data from 72,998 Japanese women who were asymptomatic and aged 40 to 49 years with no previous cancer history and a life expectancy of at least 5 years.
Researchers randomly assigned the women to receive a standard mammogram (n = 36,139) or a mammogram plus ultrasound (n = 36,859).
Overall, more cancers were detected in the intervention group (184 vs. 117; P = .0003).
The sensitivity appeared significantly higher in the ultrasound arm. Ninety-one percent (95% CI, 87.2-95) of women in the intervention cohort had their cancer correctly identified compared with 77% (95% CI, 70.3-83.7) of the control group (P = .0004).
However, the specificity of screening in the ultrasound cohort was lower (87.7% vs. 91.4%; P ˂ .0001)
Further, the addition of ultrasound to mammography detected more cancers at an early stage (stage 0 or 1; 144 vs. 79 stage; P = .0194).
Researchers also observed a decrease in the incidence of interval cancers among women in the intervention arm, (0.05% vs. 0.1%; P = .034). Of these interval cancers, 89% of those in the intervention group and 77% of those in the control group were invasive cancers.
The researchers indicated a limitation of these findings may be that because sensitivity and specificity were calculated based solely on data from an initial screening, the findings cannot apply to repeat screening.
“Our results suggest that adding ultrasound to mammography results in more accurate screening results for women in Japan, which could ultimately lead to improved treatment and reduced deaths from the disease,” Ohuchi said in a press release. “Further work will now be needed to see if these results can be extended to other countries in Asia. In addition, long-term follow-up of these results will determine whether including ultrasound tests in breast cancer screening ultimately affects the likelihood of successful treatment and survival, as we would expect.”
These findings are important because the trial focused on younger, average-risk women rather than older, higher-risk women, the population that makes up most trials in the U.S., Martin J. Yaffe, PhD, professor in the department of medical biophysics, and Roberta Jong, MD, FRCPC, associate professor in the department of medical imaging at University of Toronto, wrote in an accompanying editorial.
However, they also cautioned that there are several challenges to using ultrasonography for screening.
“More time is needed per examination than for mammography,” they wrote. “Additionally, recall of women without cancer is deemed harmful by some critics of screening, but ultrasonography would be likely to result in more recalls, more follow-up after shorter intervals, and lower positive predictive value for biopsy than mammography. Automated breast ultrasonography systems would greatly facilitate the screening process, but outcomes must be at least equal to those of the handheld systems that at present are the mainstay of practice.” – by Anthony SanFilippo
Disclosure: The researchers, Yaffe and Jong report no relevant financial disclosures.