Development of new technologies for reliable early detection of cancer from biological fluids via minimally invasive methods is still a high priority. Cancer cells often overexpress characteristic surface receptors, which provide an opportunity for early diagnosis of disease. This paper presents the first application of nanotube-based electronic devices for targeting overexpressed surface receptors in cancer cells upon interaction with specific monoclonal antibodies (mAb) adsorbed to single wall carbon nanotube (SWNT) devices. Monoclonal antibodies specific to cell surface antigens overexpressed on cancer cells can be adsorbed to single wall carbon nanotube (SWNT) devices, resulting in a drop in conductance. Application of human BT474 and MCF7 breast cancer cells increased the conductance of the insulin-like growth factor 1 receptor (IGF1R) specific mAB-SWNT devices. The degree of increase in conductance of the devices due to live cancer cell application was proportional to the number of overexpressed surface receptors in cancer cells.