The first randomized trial of population screening with adjunctive ultrasound has found a significantly higher breast cancer detection rate than mammography alone, suggesting that the modality may offer a low-cost way to increase sensitivity and detection rates of early cancers in women with dense breast tissue.
What’s more, unlike most previous studies, this one looked at asymptomatic women at average risk rather than those at moderate or high risk.
The work, called J-START for Japan Strategic Anti-cancer Randomized Trial, was published online Nov. 5 in The Lancet.
Assessing 72,998 women twice in two years in 42 sites across Japan, Noriaki Ohuchi, PhD, of Tohoku University, found that sensitivity was significantly higher in the intervention group than among the control patients (91.1 percent vs 77).
- More cancers were detected in the intervention group (184 [0.5 percent]) than in the control group (117 [0.32 percent]).
- Of 184 cancers detected in the intervention group, 128 (70 percent) were invasive, as compared with 86 (74 percent) of 117 in the control group.
- Cancers were more frequently of clinical stage 0 and I in the intervention group compared with the control group (144 [71.3 percent] vs 79 [52 percent].
On the latter finding, the authors note in their discussion that, because stage I breast cancers are more likely to be correctly diagnosed than stage 0 cancers and have better survival than more advanced tumors, “this distribution supports the potential for reduction of mortality or incidence of advanced breast cancer.”
Mitigating the enthusiasm the trial is likely to generate over sensitivity, specificity was significantly lower than mammography alone (87.7 vs 91.4)—meaning the adjunctive ultrasound increased chances of false positives.
The authors call for long-term studies to further assess the pros and cons of adjunctive ultrasound.
In an accompanying opinion piece in The Lancet, Martin Yaffe, PhD, and Roberta Jong, MD, both of the University of Toronto, write that the results of the J-START trial are likely to be generalizable to Asian and non-Asian populations of women with small, dense breasts.
“The ability of Ohuchi and colleagues to achieve effective ascertainment of deaths due to breast cancer will be a crucial feature of this trial,” they add.
Yaffe and Jong also note challenges to using ultrasound for high volume screening, including the longer time needed per exam as compared with mammography.
Without specifying adjunctive ultrasound versus ultrasound only, they express concern over the likelihood of the modality resulting 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,” Yaffe and Jong conclude.