Diagnosis of breast cancer using ductal epithelial impedance spectroscopy

Abstract

Bioimpedance approaches to breast cancer diagnosis generally use surface electrodes, which pass a signal through the breast to identify changes in impedance. We have developed a different technique that non-invasively passes an imperceptible electrical current through the nipple to the terminal ducts in the breast to identify changes in impedance due to hyperplasia and depolarization across the ductal epithelium where breast cancer develops. Electrical contact with ductal epithelium was established non-invasively, using a nipple electrode in 200 women scheduled for breast biopsy. Transepithelial potential (TEP) and transepithelial impedance were obtained over a frequency range (0.1 Hz - 60 kHz) and processed using a frequency response analyzer/sine-wave correlation technique. In patients with malignant (n=70) or proliferative lesions (n=58) the TEP was depolarized by 10 ± 2 mV (mean ± SEM, (p<0.025). Transepithelial resistance (Re) of the ducts and skin was significantly different depending on pathology. Ductal-Carcinoma-in- situ or small invasive cancers <10mm (n=40) had a Re 460 ± 80 kΩ compared with a Re of 34 ± 5 kΩ in larger cancers (>10mm), (n=30), (p < 0.001). In the benign group, 58 of the lesions where found to show hyperplasia and had a Re of 218 ± 50 kΩ compared with nonproliferative benign (n=72) 120 ± 19 kΩ (p < 0.001). The transepithelial capacitance of the ductal system increased two-fold in tumors larger than 10mm (p < 0.002). During cancer development increases in electrical resistance dominate the ductal epithelial profile, whereas later as breast tumors become invasive and cell mass increases, resistance decreases and tumor capacitance increases. © Springer-Verlag 2007.