Photodynamic therapy for skin field cancerization: an international consensus. International Society for Photodynamic Therapy in Dermatology.

Field cancerization is a term that describes the presence of genetic abnormalities in a tissue chronically exposed to a carcinogen. These abnormalities are responsible for the presence of multilocular clinical and sub-clinical cancerous lesions that explains the increased risks of multiple cancers in this area. With respect to the skin, this term is used to define the presence of multiple non-melanoma skin cancer, its precursors, actinic keratoses and dysplastic keratinocytes in sun exposed areas. The multiplicity of the lesions and the extent of the area influence the treatment decision. Providing at least equivalent efficacy and tolerability, field directed therapies are therefore often more worthwhile than lesion targeted approaches. Photodynamic therapy (PDT) with its selective sensitization and destruction of diseased tissue is one ideal form of therapy for this indication. In the following paper the use of PDT for the treatment of field cancerized skin is reviewed and recommendations are given for its use.