Photodynamic Therapy of Human Undifferentiated Thyroid Carcinoma–Bearing Nude Mice Using Topical 5-Aminolevulinic Acid

Abstract

We determined and evaluated the effect of photodynamic therapy (PDT) using topical 5-aminolevulinic acid (ALA) cream in treating human undifferentiated thyroid carcinoma (UTC)-bearing nude mice. UTC constitutes almost 10% of thyroid cancers and shows a very poor response to chemotherapy. Today PDT with topical ALA is successfully used for the treatment of a variety of neoplastic and non-neoplastic diseases. UTC tumor was implanted in the right flank of the nude mice after anesthesia. When the actual tumor size reached about 345 mm3, all mice were divided randomly into a treatment group (n = 10) and a control group (n = 10). ALA cream was applied to tumors in treated mice and left on for 6 has a retention interval; then the tumors were irradiated by a 633-nm diode laser with an incident dose of 60 J/cm2. The tumor volumes were measured 7, 14, and 21 days after PDT in both groups. The percentage of tumor growth delay after PDT was calculated. All mice were sacrificed and the tumor weights were determined 21 days after PDT. Mean tumor volumes on 21 days after PDT were 1141.19 +/- 153.74 mm3 in the treated group and 2370.75 +/- 300.42 mm3 in the control group. The percentage of tumor growth delay was -48.13 +/- 13.76 7 days after PDT, -54.9 +/- 8.83 14 days after PDT, and -51.11 +/- 8.95 21 days after PDT. Mean tumor weights 21 days after PDT were 1.78 +/- 0.32 g in the treated group and 3.60 +/- 0.60 g in the control group. There were significant differences (p < 0.001) in mean tumor volume and weight between the treated and control groups after PDT. PDT is effective in delaying the growth of UTC-bearing nude mice using topical ALA cream and laser light with inappropriate parameters. ALA cream as a topically applied photosensitizer was effective, safe, and convenient in PDT.