[Animal experiment studies of laser effects on lymphatic vessels. A contribution to the discussion of laser surgery segmental resection of carcinomas].

Background: The potential effect of laser surgery on the process of lymphogenic metastases is subject to controversy. In this context it would be of interest to identify a morphological basis for an increased intraoperative entry of tumor cells into the lymphatic system during resection of advanced carcinomas in two or more pieces via laser surgery.

Methods: The tissue effect of laser incisions (CO2 laser: 3030 W/cm2; Nd:YAG-laser: 3180 W/cm2) on the lymphatics of the buccal mucosa in 60 Wistar rats was studied by light microscopy, histochemistry, and lymphography during surgery and subsequent wound healing. These incisions were compared to conventional scalpel incisions.

Results: No lymphatic vessels were detected in the zone of carbonization, they were mostly dilated whereas in the zone of edema. In the zone of necrosis, the lymphatic were occluded by coagulation. The mid and long-term effect of the laser light on the regeneration of lymphatics was mainly correlated to wound healing which--when compared to conventional surgery--is delayed after laser surgery. Following scalpel incision, the first lymphatics enter the wound region after 4 days, a opposed to 10 days following laser surgery. Intact continuity of the lymphatic vasculature was detectable 15 days after scalpel incision and 42 days after laser incision. The regeneration of lymphatics was slightly more delayed after CO2 laser incision than after Nd:YAG laser incision.

Conclusion: The results of this study do not indicate that the laser resection of carcinomas facilitates an intraoperative entry of tumor cells into the lymphatic vasculature. These experimental results verify clinical reports which do not observe an increased frequency of postoperative metastases after laser resection of carcinomas in two or more pieces.