Preliminary low-dose photodynamic exposure to skin cancer with chlorin e6 photosensitizer.

BACKGROUND:The study aimed to investigate the chlorin e6 photosensitizer distribution in the tumor and tumor border (5 mm) during low-dose photodynamic treatment and to increase the effectiveness of the therapy for skin neoplasms. METHODS:Sensitized boundaries of neoplasms were evaluated by video fluorescence imaging. The study of changes in the chlorin e6 distribution before/after photodynamic therapy and in the process of low-dose photodynamic exposure was carried out by the method of spectral fluorescence diagnostics. RESULTS:All 19 patients with basal-cell skin cancer had a contrast of chlorin e6 accumulation compared to normal tissues. 3 hours after intravenous administration of the photosensitizer at a dose of 1 mg/kg, the chlorin e6 concentration was: in normal tissues - 0.18 mg/kg, in the tumor - 1.26 mg/kg, in the tumor border - 0.63 mg/kg. In most cases, the fluorescence indices of chlorin e6 in tumor tissues after low-dose photodynamic therapy increased and exceeded the values before light exposure. CONCLUSION:Low-dose photodynamic therapy seems to be an optimal method for treating select skin neoplasms, which does not cause severe pain in patients during the light exposure and allows for local increase of the photosensitizer concentration in tumor tissues. This method of photodynamic therapy can improve the effectiveness of thе treatment.