PHOTODYNAMIC THERAPY USING 5-AMINOLEVULINIC ACID FOR PREMALIGNANT ANDMALIGNANT LESIONS OF THE ORAL CAVITY

BACKGROUND. Premalignant changes in the mouth, which are often widespr ead, are frequently excised or vaporized, whereas cancers are treated by excision or radiotherapy, both of which have cumulative morbidity. Photodynamic therapy (PDT) is another option that produces local tissu e necrosis with light after prior administration of a photosensitizing agent. This heals with remarkably little scarring and no cumulative t oxicity. This article describes the use of PDT with the photosensitizi ng agent 5-aminolevulinic acid (ALA) for premalignant and malignant le sions of the mouth. METHODS. Eighteen patients with histologically pro ven premalignant and malignant lesions of the mouth were sensitized wi th 60 mg/kg ALA by mouth and treated with laser light at 628 nanometer s (100 or 200 Joules/cm(2)). The results were assessed macroscopically and microscopically. Biopsies were taken immediately prior to PDT for fluorescence studies, a few days after PDT to assess the depth of nec rosis, when healing was complete, and up to 88 weeks later. RESULTS. T he depth of necrosis varied from 0.1 to 1.3 mm, but complete epithelia l necrosis was present in all cases. All 12 patients with dysplasia sh owed improvement (repeat biopsy was normal or less dysplastic) and the treated areas healed without scarring. Some benefit was observed in f ive of six patients with squamous cell carcinoma, but only two became tumor free (one with persistent mild dysplasia). No patient had cutane ous photosensitivity for longer than 2 days. CONCLUSIONS. PDT using AL A for dysplasia of the mouth produces consistent epithelial necrosis w ith excellent healing and is a simple and effective way to manage thes e patients. Results in invasive cancers are less satisfactory, mainly because the PDT effect is too superficial with current treatment regim ens using ALA as the photosensitizing agent. (C) 1996 American Cancer Society.