Metabolic activity and DNA integrity in human hepatic metastases after interstitial laser coagulation (ILC)

Background and Objective: For investigations into interstitial laser coagul ation (ILC) of solid tumors, tissue whitening is used as a parameter for th e extent of coagulation. This obvious demarcation is associated with global thermal denaturation, but it is not clear whether this finding is a good i ndicator of the exact outer boundary of the lethal tissue effect. Study Design/Materials and Methods: ILC with portal inflow occlusion was pe rformed in human hepatic metastases of colorectal carcinoma directly after surgical resection (n = 5) or before surgical resection (n = 5) with laser parameters adapted to tumor diameter. Mitochondrial NADH-diaphorase activit y and DNA integrity were assessed by histoenzymatic staining. Results: In 7 of 10 tumors (mean diameter, 3.7 cm), an area of macroscopic coagulation (mean diameter, 4.2 cm) encircled the tumor in all three axes. Macroscopic coagulation corresponded to absent metabolism and disintegrated DNA. Furthermore, the macroscopic volumes of coagulation produced in tumor were comparable to the dimensions in normal porcine liver with the same la ser parameters. Conclusion: ILC with portal inflow occlusion results in areas with complete cell avitality in the zone of tissue whitening in human hepatic liver meta stases. Lasers Surg. Med. 28:80-86, 2001. (C) 2001 Wiley-Liss, Inc.