THE LASER TREATMENT OF EXPERIMENTAL MALIGNANT TUMOURS.

Some of the results of experiments performed during the past two years to assess effects of laser energy on experimental malignant tumours are reviewed. Twenty types of malignant tumours (most in the cheek pouch and 11 of human origin) were treated in over 700 Syrian hamsters. Results of laser treatment of malignant melanomas and thyroidal carcinomas are presented. A human patient with malignant melanoma treated by laser energy is described. Investigation of thermal effect revealed that the laser-treated tumour remained warm for about one minute, while the cautery-treated tumour cooled to normal temperature in five seconds. Direct action of laser on superficial tumours is possible; deeper lesions must be exposed surgically. Laser energy has a selective effect on certain malignant tumours, resulting in their progressive regression and ultimate dissolution. All hamsters with implanted malignant melanomas and carcinomas of human origin, after completion of a course of laser treatment, showed no gross or histologic evidence of tumour up to the date of last observation.