The patient was a 70-year-old male with superficial hypopharyngeal cancer and advanced cancers of the esophagus and stomach. In his past history, a cardiac pacemaker was implanted for sick sinus syndrome. Further examination showed esophageal cancer had metastasized to the cervical lymph nodes and invaded the trachea. There was no surgical indication. In terms of chemoradiotherapy, it was thought to be possible because the patient was not pacemaker- dependent and radiotherapy could be planned in such a way as to keep the dose to the pacemaker as low as possible. Electrocardiogram was monitored during the treatment. In addition to the usual observation, the patient's cardiac symptoms and pacemaker status were assessed before and soon after the completion of radiotherapy. S-1 was selected as a concomitant chemotherapy. In liaising with the cardiologist and radiologist, chemoradiotherapy was achieved without pacemaker malfunction, and shrinking of tumors was also detected.