Adverse Effects of Topical Photodynamic Therapy

A Consensus Review and Approach to Management

S.H. Ibbotson; T.H. Wong; C.A. Morton; N.J. Collier; A. Haylett; K.E. McKenna; R. Mallipeddi; H. Moseley; L.E. Rhodes; D.C. Seukeran; K.A. Ward; M.F. Mohd Mustapa; L.S. Exton

Disclosures

The British Journal of Dermatology. 2019;180(4):715-729. 

In This Article

Abstract and Introduction

Abstract

Background: Topical photodynamic therapy (PDT) is widely used to treat superficial nonmelanoma skin cancer and dysplasia, and is generally well tolerated. However, as with all treatments, adverse effects may occur and awareness may facilitate approaches to prevention and management.

Objectives: To review the available evidence relating to the adverse effects of topical PDT, to help inform recommendations in updated clinical guidelines produced by the British Association of Dermatologists and British Photodermatology Group, and the efficacy of preventative and therapeutic approaches.

Methods: This review summarizes the published evidence related to the adverse effects of topical PDT and attempts to interpret this evidence in the context of patient risk and management.

Results: Pain and discomfort during PDT are acute adverse effects, which can be minimized through the use of modified and low-irradiance PDT regimens and do not therefore usually limit successful treatment delivery. Other adverse effects include the risk of contact allergy to photosensitizer prodrugs, although this is rare but should be kept in mind, particularly for patients who have received multiple PDT treatments to larger areas. There are no other significant documented longer-term risks and, to date, no evidence of cumulative toxicity or photocarcinogenic risk.

Conclusions: Topical PDT is usually well tolerated, reinforcing the utility of this important therapeutic option in dermatology practice. The main acute adverse effect of pain can typically be minimized through preventative approaches of modified PDT regimens. Other adverse effects are uncommon and generally do not limit treatment delivery.

Introduction

Topical photodynamic therapy (PDT) is widely used to treat superficial nonmelanoma skin cancer and dysplasia. As with any therapeutic approach, the benefit/risk profile must be taken into account on an individual patient basis; in general, PDT is well tolerated. Historically, PDT-induced pain has been a potentially limiting factor, but with optimization of treatment parameters, such as the introduction of lower irradiance regimens, pain is now uncommonly a major issue. Expected 'adverse' effects of a phototoxic insult also include inflammation, manifest as erythema, exudation and sometimes urticaria. Other side-effects are uncommon and include scarring, altered hair growth or pigmentary change and allergic reactions. The theoretical risk of carcinogenesis with cumulative PDT treatments is unproven; indeed, PDT can be considered as a prophylactic approach in high-risk patients, such as the immunosuppressed. This review summarizes the current evidence relating to the adverse effects of topical PDT as part of the guideline updating project on this subject,[1] and interprets this evidence in the context of patient risk (Table 1).

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