PHOTODYNAMIC THERAPY OF NONMELANOMA MALIGNANT-TUMORS OF THE SKIN USING TOPICAL DELTA-AMINO LEVULINIC ACID SENSITIZATION AND LASER IRRADIATION

Eighty basal cell carcinomas (BCCs) in 21 patients, 10 lesions of Bowe n's disease in three patients, and four lesions of cutaneous T-cell ly mphoma in two patients, were treated with photodynamic laser therapy ( PDT), using topical application of the haem precursor delta-amino levu linic acid (ALA). The diagnoses were confirmed histologically prior to treatment. Fifty-five of the BCCs were superficial lesions, and 25 we re nodular. Of the 80 BCCs, 39 (49%) were located on the trunk, 36 (45 %) on the head and neck region, four (15%) on the leg and one on the a rm. The two principal locations of the 10 Bowen's disease lesions were the leg (50%) and the trunk (40%). The T-cell lymphoma lesions were l ocated on the shoulder and on the arm. A water-in-oil based cream cont aining 20% ALA was applied to the lesions, with a margin of about 10-2 0 mm beyond the visible tumour border, 4-6 h before the laser procedur e. During this period of time the highly fluorescent and photodynamica lly active substance protoporphyrin IX (Pp IX) is synthesized via the haem cycle. Laser-induced fluorescence (LIF) was used for real-time mo nitoring of the Pp IX distribution in the tumour and in the normal sur rounding skin, before and after treatment in all patients. Before lase r treatment the Pp-IX distribution demonstrated by LIF showed a demarc ation between tumour and normal skin of about 15:1 for BCC and Bowen's disease, and 5:1 for T-cell lymphomas. Laser light from a pulsed freq uency-doubled Nd:YAG laser pumping a dye laser with light emission at 630 nn was used for the therapy. The power density in the irradiation was kept below 110 mW/cm(2), in order to avoid hyperthermal effects. A total energy of 60 J/cm(2) was delivered for 10-20 min, depending on the tumour size. A complete response rate of 100% in superficial BCCs and 64% in nodular BCCs occurred after a single laser treatment, and a response rate of 100% was achieved after one additional. treatment in the nodular BCCs. in the Bowen's disease lesions a complete response of 90% was obtained with a single treatment. Two of the four T-cell ly mphomas resolved completely. The follow-up time was between 6 and 14 m onths.