A synthesis of the world's guidelines on photodynamic therapy for non-melanoma skin cancer.

Photodynamic therapy (PDT), using topically administered photosensitizing agents, is widely approved as a treatment for certain nonmelanoma skin cancers. As a tissue-sparing non-surgical modality, there is great potential for PDT to enhance the choice of therapies available to treat, and potentially prevent, skin cancer. Treatment-specific guidelines have assessed the evidence for various photosensitizing agents and light sources, dosimetry, and evaluate reported adverse effects. Discomfort is frequently experienced during treatment but no analgesia was required in most pivotal lesion-directed studies. Durability of response has been assessed with studies of PDT for basal cell carcinomas (BCC) extending to 5 years and beyond, 2 years for Bowen's disease and up to 1 year for actinic keratoses (AK). Disease-specific guidelines consider the place for topical PDT in routine clinical practice recognizing that PDT is typically office/clinic-based and usually initiated by specialists. Where updated guidelines are awaited, national and international consensus publications offer recommendations, including on the use of daylight to activate the photosensitiser for treating AK. Reviewed studies indicate equivalent efficacy of daylight PDT, but greatly reduced pain compared with conventional PDT. Guidelines and consensus publications also consider the place of PDT in treating skin lesions arising in organ transplant recipients and in the potential for PDT to delay/prevent the development of nonmelanoma skin cancers. There is now a substantial evidence-base to support the use of topical PDT in routine clinical practice with daylight PDT indicated for AK, providing suitable outside climate, whilst conventional PDT remains suitable for AK, Bowen's Disease, superficial and certain thin nodular BCC.