Abstract

Among the efficient cancer treatments, photodynamic therapy (PDT) is one of the therapies inducing rapid apoptosis of cancer cells while causing minimal damage to surrounding normal tissue. We studied the effect of PDT on the adenocarcinoma in BALB/-c mice of homograft model, and the following results were obtained. Apoptosis occurred up to 3 mm in depth from the surface in the first 1 hour after PDT applied, and subsequently the counts were increased in the deeper portion. A remarkable apoptosis observed up to 6 mm in depth shows that the light in use could not penetrate more than 6 mm of tissue. Tissue necrosis was identified in the deeper area of the tumor 6 hours later or thereafter. This necrosis seemed to occur as an indirect effect of vascular obstruction resulting from the damage of endothelial cells which was induced by selective collection of photosensitizer in the endothelial cells of newly forming vessels as well as in the cancer cells. These results indicate that the effective depth of PDT is greater than the depth of light penetration.

• Keywords: Photodynamic therapy;Apoptosis;Necrosis