[The efficacy and limitations of laser surgery in malignant tumors]

Using rats with tumor transplanted into the subcutaneous tissue, tumor resections done with either an ordinary scalpel or a laser scalpel were compared from the viewpoints of tumor recurrence and survival time. It was found that tumor resection using the laser scalpel and laser irradiation of the field after tumor resection were effective in preventing recurrence. With this concept in mind, 286 operations involving laser surgery were performed, including 179 for malignant tumor, most of which were cancers of the liver, esophagus, stomach and colon. Laser surgery for hepatoma and other malignant tumors yielded better results than ordinary surgery. Another experimental study of PDT (photodynamic therapy) for malignant tumor of the parenchymal organs was carried out. The uptake of HpD (hematoporphyrin derivatives) by the liver was as much as 1.5 times that by the digestive tract. The concentration of HpD in the tumor tissue of WKA rats with DAB hepatic tumor was twice that in liver tissue. However, the difference in HpD concentration between the tumor tissue and liver tissue is not large enough for PDT and this point requires further study.