Diode laser and antitumoral interstitial hyperthermia

A randomized study of interstitial hyperthermia with diode laser was performed on 40 Swiss nu/nu mice. The series was divided as follows: group 1 a control group; and group 2 treated by diode laser. The tumor model was a subcutaneous HT29 colonic carcinoma treated at the same size. The diode laser (830 nm) was applied through a 300 micrometers optic fiber implanted in the tumor and delivered at a power output of 200 mW and 1800 sec exposure time (360 J). The temperature range was 46 degree(s)C in the center of tumor and 42 degree(s)C in its peripheral part. In both groups, the tumor was removed 3 days after laser treatment. The tumor volume (TV) was evaluated and compared using nonparametric tests (Kruskal Wallis). Microscopic examination of tumors showed extensive and complete necrosis in group 1. By day 30 after removal the tumoral recurrence rate was 20% in group 2 versus 55% in group 1. The technical advantages of diode laser are pointed out.