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Background/Objectives Solar (actinic) keratosis (AK) is an emergent concern worldwide and is associated with an increased risk of development of non-melanoma skin cancer, especially squamous cell carcinoma. Daylight-mediated photodynamic therapy (DL-PDT) using methyl aminolaevulinate cream has proved to be an effective, nearly painless, and more convenient alternative to conventional PDT for the treatment of AK. In a phase III, randomised, controlled trial performed in Australia, the mean irradiance (light intensity) received by patients during DL-PDT treatment, assessed via a spectroradiometer, was 305 W/m2 (min. 40 to max. 585 W/m2) with similar efficacy irrespective of intensity or dose. The objective of the present meteorological study was to assess the suitability of natural daylight to perform DL-PDT for the treatment of face and scalp AK during different periods of the year and different geographical locations and latitudes across Australia. Methods To determine daylight irradiance during a complete year in eight different geographical locations throughout Australia, we used meteorological software (Meteonorm, Meteotest, Bern, Switzerland), and available solar radiation and weather data from 1986–2005. Results The average daily irradiance remained within the levels (40–585 W/m2) measured during the clinical DL-PDT study in Australia, throughout the year and in all geographical locations investigated (yearly average from Darwin 548 W/m2 to Hobart 366 W/m2). Conclusions DL-PDT for the treatment of face and scalp AK in Australia can be performed effectively throughout the entire year as long as weather conditions permit daylight exposure and allow participants to remain under direct light for 2 h.

Photodynamic therapy (PDT) of non-melanoma skin cancers currently carries failure rates of 10-40%. The optimal irradiation protocol is as yet unclear. Previous studies showed profound immunosuppression after PDT, which may compromise immune-mediated clearance of these antigenic tumors. Slower irradiation prevents immunosuppression in mice, and may be at least as effective as high-fluence-rate PDT in preliminary clinical trials. The photosensitizers 5-aminolaevulinic acid and/or methyl aminolaevulinate were applied to discrete areas on the backs of healthy Mantoux-positive volunteers, followed by narrowband red light irradiation (632 nm) at varied doses and fluence rates. Delayed type hypersensitivity (Mantoux) reactions were elicited at test sites and control sites to determine immunosuppression. Human ex vivo skin received low- and high-fluence-rate PDT and was stained for oxidative DNA photolesions. PDT caused significant, dose-responsive immunosuppression at high (75 mW cm(-2)) but not low (15 or 45 mW cm(-2)) fluence rates. DNA photolesions, which may be a trigger for immunosuppression, were observed after high-fluence-rate PDT but not when light was delivered more slowly. This study demonstrates that the current clinical PDT protocol (75 mW cm(-2)) is highly immunosuppressive. Simply reducing the rate of irradiation, while maintaining the same light dose, prevented immunosuppression and genetic damage and may have the potential to improve skin cancer outcomes.

Background Two phase III trials of photodynamic therapy (PDT) with BF-200 ALA, a recently approved nanoemulsion formulation of 5-aminolaevulinic acid (ALA) demonstrated high clearance rates in mild-to-moderate actinic keratosis (AK). The comparison to a registered methyl aminolaevulinate (MAL) cream demonstrated significantly superior total patient clearance rates. Objectives To evaluate long-term efficacy and safety of PDT for AK 6 and 12 months after the last PDT with BF-200 ALA, MAL or placebo. Methods The follow-up phase (FUP) was performed with patients of two phase III studies. Both studies compared BF-200 ALA with placebo, one of the studies additionally with MAL. Overall recurrence rates and various subgroups (light source, lesion severity, lesion location, complete responders after first PDT) were assessed 6 and 12 months after the last PDT. Results Recurrence rates were similar for BF-200 ALA and MAL, with a tendency to lower recurrence rates for BF-200 ALA. The proportion of patients who were fully cleared during PDT and remained completely clear for at least 12 months after PDT were 47% for BF-200 ALA (both studies) and 36% for MAL treatment. The subgroup that was illuminated with narrow wavelength LED lamps reached 69% and 53% for BF-200 ALA (both studies, respectively) and 41% for MAL. No safety concerns were reported. Conclusions The FUP data confirmed the high efficacy and safety of PDT with BF-200 ALA. The slightly lower recurrence rates after BF-200 ALA treatment compared with MAL treatment enhanced the better treatment outcome due to the significantly superior efficacy.

Methyl aminolaevulinate photodynamic therapy is increasingly practiced in the treatment of actinic keratoses, Bowen's disease and basal cell carcinomas. This method is particularly suitable for treating multiple lesions, field cancerization and lesions in areas where a good cosmetic outcome is of importance. Good treatment routines will contribute to a favourable result. The Norwegian photodynamic therapy (PDT) group consists of medical specialists with long and extensive PDT experience. With support in the literature, this group presents guidelines for the practical use of topical PDT in non-melanoma skin cancer.