Introduction
The effectiveness of hyperthermia for deep-seated intrathoracic tumors has not yet been established 1)2,) 3, ).
High RF output over 1000W is required for tumors such as lung and esophageal cancer to acquire an
effective tumoricidal temperature We improved the cooling of the overlay bolus to decrease thermoesthesia
on the body surface. In addition, we employed body earthing to remove residual electric current from the
body surface to allow a higher RF output to be delivered 5,6)7, ).T o our knowledge, no studies have examined
the side effects of hyperthermia using high RF output over 1000W. The side effects for intrathoracic
tumors included thermoesthesia due to overheating of the subcutaneous fatty layer, fatigue and elevations
of blood pressure and pulse rate. Concerning long-term effects, degradation of cardiac and pulmonary
function and esophageal ulcer were reported 8),9)W. e investigated here, the side effects of 115 cases of
intrathoracic tumors based on the evaluation of safety of hyperthermia with a high RF output.