ABSTRACT
BACKGROUND: Thermotherapy has achieved remarkable therapeutic effect on patients with esophageal cancer. However, there are still some problems which cannot be answered today, such as the damage of esophageal mucosa during deep thermotherapy when metal stent is placed in esophagus. OBJECTIVE: To study the metal stent-caused damages to esophageal mucosa of pigs in radiofrequency hyperthermia. DESIGN, TIME AND SETTING: Observational study which was performed in the Department of Tumor, Affiliated Hospital of Luzhou Medical College from October 2004 to January 2005. MATERIALS: 13 pigs weighing 35-40 kg were used in this study. Esophagus stent of memory alloy with membrane was provided by Zhiye Medical Apparatus Institute of Changzhou, China METHODS: Five points were located for measurement, i.e. the middle of the stent, the exit of the stent, 2 cm and 4 cm a distance from the exit and 4 cm from the entrance. Esophagus of 13 pigs was heated for 30 minutes by SR-1000 radiofrequency hyperthermia machine in frequency of 40.82 MHz, pole plate of 25 cm Ⅱ 25 cm and power of 500-700 W. MAIN OUTCOME MEASURES: The esophageal mucosa was observed with naked eyes. And optical microscopy was used to observe the changes of the esophageal mucosa. RESULTS: Because one pig died of anesthesia and there were troubles of thermal detector lines in 4 pigs, only 8 pigs were included in the final analysis. Level of damage of esophageal mucosa on five temperature checkpoints was observed from grade 0 to 1 in naked eyes, and the difference of damaged level between five checkpoints was not obvious in statistics (H=2.0, P=0.157). Level of the damage was observed from grade 0 to 2 in microscope, and the difference was not obvious in statistics too (H=2.734, P=0.255). CONCLUSION: Influence of the metal stent on esophageal mucosa can be neglected in radiofrequency hyperthermia, and metal stent does not cause obvious mechanical damage or thermal damage to esophageal mucosa of pigs. It is safe and feasible to carry out radiofrequency hyperthermia on placed metal stent esophagus.