Compared to standard digital mammography, 3D mammography (tomosynthesis) does improve the chance of finding cancer in most breasts. However, in women with extremely dense breasts, studies have shown mixed results as to whether 3D mammograms find more cancers than 2D mammograms. 3D does reduce the chance of having to return for additional diagnostic imaging for a false positive finding (false alarm).
Studies indicate there is benefit from screening ultrasound even after 3D mammography. Four large-scale studies [1-4] showed that ultrasound significantly improved detection of cancer even after the combination of 2D and 3D mammography in dense breasts. However, on average, ultrasound will also show more areas which need follow-up than does mammography. Some of those “finds” will be cancer, but the vast majority of these additional findings, determined after further imaging or biopsy, will be false positives.
1. Tagliafico AS, Mariscotti G, Valdora F, et al. A prospective comparative trial of adjunct screening with tomosynthesis or ultrasound in women with mammography-negative dense breasts (ASTOUND-2). Eur J Cancer 2018; 104:39-46
2. Destounis S, Arieno A, Morgan R. Comparison of cancers detected by screening ultrasound and digital breast tomosynthesis. Abstract 3162. In: American Roentgen Ray Society (ARRS). New Orleans, LA, 2017
3. Tagliafico AS, Calabrese M, Mariscotti G, et al. Adjunct screening with tomosynthesis or ultrasound in mammography-negative dense breasts (ASTOUND): Interim report of a prospective comparative trial. J Clin Oncol 2016
4. Dibble EH, Singer TM, Jimoh N, Baird GL, Lourenco AP. Dense breast ultrasound screening after digital mammography versus after digital breast tomosynthesis. AJR Am J Roentgenol 2019; 213:1397-1402