The combination of radiotherapy and thermotherapy has the greatest antitumor effect when delivered simultaneously. We developed and have clinically used an applicator that enables simultaneous intraluminal irradiation and hyperthermia delivery for the treatment of locally invasive esophageal carcinoma. In a phase 1 study, 40 Gy of external irradiation was delivered followed by simultaneous intraluminal hyperthermia and radiotherapy once weekly for three weeks. Intraluminal hyperthermia was delivered to the mucosal surface at 42 to 44 degrees C for 30 minutes. Intraluminal irradiation (3 Gy) was delivered to a submucosal depth of 5 mm after the first 15 minutes of hyperthermia. This treatment may increase current treatment results for locally invasive esophageal carcinoma, which have otherwise been maximized.