Topical Photodynamic Therapy in a Medical Centre: The Scottish Dermatology Experience

Topical photodynamic therapy (PDT) is widely used in dermatology for treating superficial non-melanoma skin cancer (NMSC) and dysplasia. This study aims to assess real-world outcomes of PDT in a Scottish dermatology service.

We retrospectively reviewed patients with superficial NMSC and dysplasia who underwent conventional and daylight PDT at the Photobiology Unit, Dundee, Scotland.

A total of 705 patients with 2108 NMSC and precancerous skin lesions underwent conventional PDT. Clearance at 12 months was achieved in 53.4% of actinic keratoses (AK), 71.3% of Bowenoid AK, 86.4% of Bowen's disease (BD), 89.0% of superficial basal cell carcinoma (BCC), and 89.7% of nodular BCC. On multivariate analysis, small lesion size and thin histological tumour thickness of superficial BCC were features, which were associated with likelihood of achieving clearance after PDT. Female sex, head/neck sites, larger lesion size, strong pre-treatment fluorescence intensity, fluorescence specificity, prominent treatment-induced erythema and an urticarial reaction were associated with moderate to severe pain during PDT. Daylight PDT for 77 AK patients (158 treatments) showed excellent or good outcomes in 63.3% of lesions. Higher visible light exposure is correlated with better treatment outcomes.

In real-life settings, whilst the PDT response rates of BD and selected BCC are high and consistent with clinical trial outcomes, the efficacy rates for AK appear lower than expected. This emphasizes the need for realistic expectations in chronic disease management. Through review over a prolonged period, factors associated with PDT tolerability and outcomes were identified, allowing predictive utilisation for optimizing patient-centred PDT regimens.