Systems and methods treat a tissue region. In one arrangement, the systems and methods deploy an electrode on a support structure in a tissue region at or near the cardia of the stomach. The support structure has a proximal region and a distal region. The proximal region is enlarged in comparison to the distal region, and the electrode is carried by the enlarged proximal surface. The systems and methods advance the electrode in a path to penetrate the tissue region and couple the electrode to a source of radio frequency energy to ohmically heat tissue and create a lesion in the tissue region. In another arrangement, the systems and methods treat abnormal epithelium tissue at or near the lower esophageal sphincter by bringing an array of surface electrodes into contact with abnormal epithelium tissue. The systems and methods couple the surface electrodes to a source of radio frequency energy to ohmically heat tissue and cause necrosis of the abnormal epithelium tissue.