[Laser and cancer therapy]

Two kinds of laser were employed in the treatment of cancers of various organs: a high energy vaporization therapy by a Nd-YAG laser and a photoradiation therapy (PRT) by an argon dye laser (red light with 630 nm wave length) after i.v. administration of hematoporphyrin derivative (HpD). In the former, the lesion was vaporized with a power of 40-80 W with continuous wave or pulse wave transmitted endoscopically. Improved condition was obtained in 59.3% among 27 malignant lesions of the trachea and bronchi. The indications of this method were discussed in relation to the tumor location and type of growth. In PRT the lesion was photoradiated with a power of 100-2,000 mW for 10-30 minutes, 48 hours or more after i.v. injection of 2.5-5.0 mg/kg HpD. PRT was performed in 170 cancer cases consisting of 69 cases of lung cancer, 9 cases of esophageal cancer, 22 cases of gastric cancer, 18 cases of bladder cancer and other 52 cases of various organs. In 29 cases of early stage cancers complete tumor remission was obtained in 65.5%, especially in early stage central type lung cancer. Local effect was obtained in all advanced cases. The method is also available to reduce the extent of resection or to widen the indications of surgery preoperatively. However, there are many problems in PRT such as the activation mechanism of HpD, diagnosis of early stage cancer candidates for PRT, indications and limitations.