Since middle of 1970s, endoscopic laser treatment had been applied hemostasis in the upper GI tract by Frülimorgen P. et al., Dwyer R. M. et al., Kiefhaber P. et al. and so on. At the beginning of 1980s,. Nd: YAG laser endoscopy was applied clinically for the treatment of the GI tumors. From 1984 we have been developing the Nd: YAG laser contact method with several contact probes and a computer-controlled Ncl: YAG laser hyperthermia (Laserthermia) system in cooperation with Surgical Laser Technologies Japan Co.. The experimental studies and technical developments of Nd: YAG laser endoscopy in our hospital were discussed in this paper.
Nd: YAG laser contact method with various kinds of contact probes could treat every type of lesions as endoscopic photocoagulation, vaporization, mucosal cutting, Laserthermia. Actually clinical effects by contact method had been risen about 15-25%, higher than those by the conventional non-contact method. However, it was difficult treating all of the cases concering GI tumors by laser endoscopy alone. Therefore many patterns of the combination therapy of the contact laser methods and the other endoscopic therapeutics and general treatments should be necessary. According to the experimental studies on the ENNG induced gastric tumor in beagle dogs and the transplanted human gastric cancer in nude mice, mucosal GI cancer could be treat by Laserthermia only. On the other hand, the stimulation in the interstitial tissue of the canine stomach and the transplanted human gastric cancer in nude mice as a increase of active collagenase and marked increase of collagen fiber may suggest specific reaction by Laserthermia. We have continuously to study whether these tissue stimulation could be benefit or not in the treatment of GI tumors.^15,16)
The contact method with various contact probes made endoscopic laser therapy easy and safe. Then it is possible to treat endoscopically not only photocoagulation and varporization but also mucosal cutting, interstitial irradiation and Laserthermia. Now we are going to study the Laserthermia by a single channel method using the newly developed Hybrid probe and therapeutic UGI fiberscope (GIF-WT; Olympus).¹⁷⁾