Effective treatment of 7,12-dimethylbenz(a)anthracene-induced hamster buccal pouch precancerous lesions by topical photosan-mediated photodynamic therapy.

BACKGROUND Previous studies found that topical photodynamic therapy (PDT) is very effective for human oral precancerous lesions. METHODS This study evaluated whether topical photosan-mediated PDT (topical photosan-PDT), using a 640-nm light-emitting diode (LED) light, is an effective treatment modality for hamster buccal pouch precancerous lesions. Fourteen 7,12-dimethylbenz(a)anthracene (DMBA)-induced hamster buccal pouch precancerous lesions were treated with topical photosan-PDT using the 640-nm LED light twice a week. RESULTS All 14 of the precancerous lesions showed a complete histologically confirmed response to the lesions after an average of 3.79 (range, 3-5) PDT treatments. Normal and precancerous pouch mucosae in the other 4 hamsters received 17 or 19 treatments of topical photosan-PDT showed no cumulative side effects. No recurrence of the lesions was found in these 18 PDT-treated hamsters after a follow-up period of 50 weeks. CONCLUSION Our findings indicate that topical photosan-PDT is a very effective treatment modality for DMBA-induced hamster buccal pouch precancerous lesions.