Summers PE, et al. - Whether millimeter-wave (mm-wave) spectroscopy affords a tool to gain insight into the dielectric properties of breast tissues was investigated, to shed light on the possibility of its use in the evaluation of surgical margins. Researchers used prospectively and consecutively obtained tumoral and non-tumoral ex-vivo breast tissue samples from 91 patients, to evaluate if a mm-wave system with a roughly hemispherical sensitive volume of ∼3 mm radius was capable to differentiate malignant breast lesions. In these samples, including malignant, fibrocystic disease and normal breast tissues, they characterized the dielectric properties of 346 sites. In this study, mm-wave spectroscopy enabled a reliable differentiation of malignant from normal, fat-rich breast tissue to a depth compatible with surgical margin evaluation needs.