���期胃癌に対するyag-opoレーザーを用いた光線力学的療法 (pdt) の臨床試験

Photodynamic therapy (PDT) is a new endoscopic method for treating malignant tumors using a photosensitizer and a laser. We employed a new pulse laser as the excitation light source for PDT to treat early gastric cancer, which is an optical parametric oscillator system pumped by a Q-switched Nd: YAG laser (YAG-OPO laser; Ishikawajima-Harima Heavy Industries, Tokyo, Japan). It has a high peak power of 700 kW and its average output is 250 mW. Because of the tunability of wavelength which is between 620-670 nm enables it to be used for various kinds of new photosensitizers.From June 1995 until December 1997, we performed a cooperative clinical trial of PDT for early gastric cancer with Photofrin InjectionR and the YAG-OPO laser. Fifteen patients were enrolled and 12 were evaluable for response. Complete responses (CR) were obtained in 75% of twelve patients, including two cases that required the second session of PDT. According to the depth of the lesion, CR was observed in all cases with mucosal carcinoma and 63% with submucosal carcinoma One case, whose tumor was 19cm2 in area, was ineligible because of its large size but the cancerous lesion was cured completely. Regarding toxicity, mild photosensitivity was seen in one case and it lasted several weeks. Another major side effect was the decrease of total protein, which was observed in six patients (40%) and it lasted several months. There were no serious abnormalities in symptoms or laboratory tests.We conclude that YAG-OPO laser has the capability of acting as the excitation light source for PDT.