Noninvasive measurement of the electrical properties of breast epithelium during the menstrual cycle: a potential biomarker for breast cancer risk.

Breast epithelia maintain an ionic and electrical gradient across the ductal lumen, which can be measured using ductal epithelial impedance spectroscopy (DEIS). Furthermore, the breast remodels itself through a secretory, proliferative, and involutional cycle each month in premenopausal women, which changes the electrical properties of the epithelium. DEIS was used to examine the electrical properties of breast epithelia in 14 normal women at multiple points during 1-2 menstrual cycles with IRB/patient consent. The epithelial resistance (Re) measured 159 +/- 26 kOmega (mean +/- SEM) in week 1 (n = 55) of menstrual cycle, when the epithelium is single layered and atrophic, increased to 217 +/- 20 kOmega (p < 0.05) by weeks 2-3 (n = 129), as the epithelium becomes more proliferative and multilayered, and reached 263 +/- 30 kOmega (p = 0.002) by week 4 (n = 75). The capacitance of the epithelium increased between week 2 and 3 of the cycle from 0.32 +/- 0.02 microF (microFarads) to 0.51 +/- 0.05 microF (p = 0.003), when the epithelial cell mass is greatest. The characteristic frequency (fC) of the epithelium, a property related to morphology and transport function, decreases progressively through weeks 1-4 of menstrual cycle from 17 +/- 3 to 11 +/- 2, 10 +/- 1, and finally to 7 +/- 1 Hz respectively (p = 0.003). This study demonstrates that the electrical properties of breast epithelium are dependent on the time during the menstrual cycle, and likely represents morphological changes in breast epithelia associated with the menstrual cycle. Patients at risk for breast cancer may have an aberrant epithelial response to estrogen and progesterone. Electrical measurements of the epithelium using DEIS, during the menstrual cycle, may represent a novel biomarker for assessing BC risk.