Canadian Expert Consensus Recommendations on the Use of Photodynamic Therapy in Actinic Keratosis.

INTRODUCTIONActinic keratosis (AK), a common ultraviolet light-induced keratinocyte neoplasm arising within chronically photodamaged skin, is associated with field cancerization and potential progression to cutaneous squamous cell carcinoma (cSCC). Photodynamic therapy (PDT) is an established field-directed treatment option for AK, but Canadian-specific practical guidance on its use remains limited. This study aimed to develop Canadian expert consensus recommendations on the overall role, positioning, technique, safety, follow-up, and use of PDT as well as PDT use in special sites and populations.

METHODSA targeted literature review was conducted using PubMed/MEDLINE for English-language publications from 2005 onward, with the final search run on October 10, 2025. Evidence was used to inform candidate statements across predefined PDT-related domains. Ten Canadian dermatologists with extensive experience with management of AK and use of PDT participated in a structured modified Delphi process, rating statements anonymously over two rounds using a 5-point Likert scale. Consensus was defined a priori as at least 75% agreement or strong agreement.

RESULTSAll 10 panelists participated in both Delphi rounds. A total of 25 consensus statements were finalized across six domains: disease framing and need for AK treatment; lesion- versus field-directed treatment strategies for AK management; role and positioning of PDT in AK management; PDT technique and modalities for AK management; PDT for AK management in special sites and populations; and PDT safety, follow-up, and combination strategies. All finalized statements achieved consensus. The panel positioned PDT as an effective field-directed strategy, particularly for non-hypertrophic facial and scalp AKs, with treatment selection guided by disease extent and the need for field cancerization with PDT; efficacy, tolerability, cosmetic outcome, and access to PDT; and patient preference for PDT.

CONCLUSIONThis Canadian expert consensus supports PDT as a practical field-directed strategy for appropriately selected patients with AK, while emphasizing individualized care, shared decision-making, realistic expectations for chronic disease management, and ongoing follow-up. Further research is needed to clarify re-treatment intervals, outcomes for special sites and populations, and optimal combination strategies.

Abstract from PubMed