INTERSTITIAL NDYAG LASER COAGULATION WITH A CYLINDRICAL DIFFUSING FIBER TIP IN EXPERIMENTAL LIVER METASTASES

Interstitial laser coagulation as a means of destructing hepatic metas tases was investigated. Colon carcinoma CC531 was implanted in the liv er of 42 Wag/Rij rats; 20 days later, tumors (5.5 +/- 0.2 mm) were exp osed to 1,064 nm Nd:YAG laser light at 4 W/cm and either 600, 1,200, 2 ,400, 3,400, or 4,800 J/cm from a 0.5 cm Helioseal(R) coated cylindric al diffuser. Temperature and fluence rate were measured at the tumor b oundary. Lesions were studied on day 2 and 36 posttreatment by light m icroscopy. Tumor proliferative activity was assessed by bromodeoxyurid ine incorporation. Liver damage and function were determined by serum liver enzymes and antipyrine clearance. Fluence rate increased during laser treatment up to 170%; mean temperature increased logarithmically up to 69.7-degrees-C. Short-term light microscopy showed coagulation necrosis of 7-11 mm without charring. Lesion size and liver enzymes in creased logarithmically with laser energy applied. No deterioration in liver function was found. At 4,800 J/cm complete tumor remission occu rred in three of four animals. This study shows the ability of interst itial laser coagulation to produce selective destruction of colonic tu mor within the liver. (C) 1994 Wiley-Liss, Inc.