Embodiments herein relate to a medical device for treating a cancerous tumor, the medical device having a first lead including a first wire and second wire; a second lead can include a third wire and fourth wire; and a first electrode in electrical communication with the first wire, a second electrode in electrical communication with the second wire, a third electrode in electrical communication with the third wire, and a fourth electrode in electrical communication with the fourth wire. The first and third electrodes form a supply electrode pair configured to deliver one or more electric fields to the cancerous tumor. The second and fourth electrodes form a sensing electrode pair configured to measure an impedance of the cancerous tumor independent of an impedance of the first electrode, the first wire, the third electrode, the third wire, and components in electrical communication therewith. Other embodiments are also included herein.