Tomosynthesis (three-dimensional mammography, digital breast tomosynthesis) significantly increases the detection rate of breast cancer thanks to imaging using 1 mm thin slices. A recently published, reputable study indicates that tomosynthesis increases the detection rate of invasive breast cancer by 41%. http://jama.jamanetwork.com/article.aspx?articleid=1883018 .
Tomosynthesis also reduces the false-positive rate of digital mammography by 15%. This means that cases that mimic cancer, even when it's not present, and lead to unnecessary further examinations are reduced by 15% due to the loss of detail and superposition in thin slices.