Basal cell carcinoma--new aspects of diagnosis and treatment.

Abstract

The incidence of basal cell carcinoma is increasing. New aspects of diagnosis and treatment are discussed in this thesis. Interferon can be used for the treatment of BCC. In paper I, 15 patients received 13.5 x 10(6) IU of alfa-2b-interferon intralesionally. Four patients healed completely whereas a 75% reduction was seen in 5 cases. Intralesional alfa-2b-interferon can reduce the number of excisions during Mohs Micrographic Surgery. Topical photodynamic therapy involves the application of ALA on the skin. In tumour cells selectively, formation of the photosensitizer Pp IX occurs. After 4 hours of occlusion of ALA the area is irradiated with light at a wavelength of 630 nm. Tumour cells are selectively destroyed during this procedure. 144/157 SBCC healed in this series and 14/18 Mb Bowen (paper II). The method is only suited for thin BCCs as the result on thicker lesions is poor (2/10 healed). The cosmetic result was generally good or excellent. Another way of utilising the tumour selectivity of Pp IX is for diagnostic purposes. Instead of illuminating with 630 nm, 365, 366 and 405 nm are used to induce a specific fluorescence. In the present paper (III), 50% of facial BCCs with ill-defined borders could be completely visualised and another 23% partly outlined. The technique did not seem to work in 27% of the cases. The critical factor using ALA is probably the relatively poor penetrance through the skin. In paper IV, microdialysis is used for pharmacokinetic studies of ALA for the first time. The concentration of ALA increases rapidly in lesional skin whereas there is virtually no penetration in healthy skin. Also, the blood perfusion in BCCs was investigated by means of laser Doppler Perfusion Imager. The perfusion in skin overlying a BCC was 2.5 fold higher compared to normal skin. For BCCs with ill-defined borders Mohs Micrographic Surgery is generally recommended. Regarding Mohs Micrographic Surgery, Sweden is underserved as only 1% of BCCs are treated with Mohs Micrographic Surgery as opposed to 30% in the US. Consequently, the Swedish cases are probably more severe. The long-term results are reported in paper V. Two hundred and twenty-eight tumours were followed for at least 5 years. The rate of recurrence was 8%. This figure is slightly higher than in international materials but surprisingly low considering the type of tumours.