Neodymium-yttrium aluminium garnet laser destruction of nonsensitized and hematoporphyrin derivative-sensitized tumors.

The injection of hematoporphyrin derivative (5 mg/kg i.v.) followed 24 hr later by a neodymium-yttrium aluminium garnet laser irradiation shows the destruction of CX1 tumors grafted on nude mice. This acidophilic necrosis occurred with a significantly increased frequency in tumors treated by hematoporphyrin derivative injection and irradiated with the neodymium-yttrium aluminium garnet laser as compared with noninjected but irradiated tumors or with injected tumors irradiated with sunlight. On the basis of our data, it seems difficult to maintain the hypothesis of singlet oxygen production as the only mechanism of the phenomenon. Further studies will be necessary to explain the necrosis that we observed.