Abstract
Objective: In high-density breasts, the detection sensitivity for lesions is low with mammography (MG) but more effective screening can be expected if it is combined with ultrasonography (US). In the present study, we examined the results of breast density-focused screening combining mammography and US.
Methods: The subjects were 6,603 persons in whom an overall evaluation of screening combining MG and US was conducted between January 2013 and December 2014. They were divided into a high-density breast group (extremely dense/heterogeneously dense) and a non-high-density breast group (scattered fibroglandular densities/almost entirely fat) and examined regarding number of cancers discovered (rate), number requiring secondary testing (rate) and positive predictive value.
Results: Among the 6,603 subjects, there were 3,492 with high-density breasts (52.9%) and 3,111 (47.1%) with non-high-density breasts. In high-density breasts, the number of cancers discovered assuming screening by MG alone was 12 (0.34%) and combination with US increased it to 20 (0.57%). For non-high density breasts, the number of cancers discovered by MG alone was 11 (0.35%) but combination with US only increased it slightly to 13 (0.42%). In addition, before the overall evaluation, the number requiring secondary testing was 539 (8.2%), but this had decreased to 454 (6.9%) after it. However, compared with MG alone, the positive predictive value for combination screening was lower (8.13% vs. 7.27%), even after the overall evaluation. Examination according to breast density produced a similar result.
Conclusion: Combination with US increased the cancer discovery rate, particularly for high-density breasts, and our findings suggested that combination could raise the efficiency of breast cancer screening. Issues for the future were considered to be reducing unnecessary secondary testing as much as possible in the overall evaluation and raising the positive predictive value.
