PHOTODYNAMIC THERAPY USING MTHPC FOR MALIGNANT DISEASE IN THE ORAL CAVITY

Photodynamic therapy (PDT) produces local tumor necrosis, on activatio n of a previously administered sensitizer with non-thermal light of an appropriate wavelength. It is attractive for treating tumors of the m outh as tissue healing is particularly good, We describe the use of th e photosensitizing agent meta tetrahydroxyphenyl chlorin (mTHPC, Fosca n(R)) for PDT of oral cancer, including patients with field cancerizat ion. Nineteen patients with histologically confirmed oral cancer (8 wi th field change disease) and one with severe dysplasia, were sensitise d with mTHPC intravenously. Activation was carried out 72-96 hr later with laser light at 652 nm using a range of light doses, The results w ere assessed clinically and histologically. Multiple biopsies were tak en during the ulcerative stages to look at the effects of PDT and afte r healing to assess the overall treatment result, All single lesions u p to stage T3 cleared after one PDT treatment (total of 6 patients), T hree out of 6 T4 tumours were also cleared. Lesions in patients with f ield change disease did less well, only 9 of 14 T1 and T2s clearing, i ncluding 4 that required extra treatments with a higher light dose, Mo st healed very well, but tongue tethering was seen in patient and anot her had necrosis in normal areas due to light scattering within the mo uth. PDT using mTHPC is a promising new treatment for patients with or al cancer, (C) 1997 Wiley-Liss, Inc.