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SUMMARY
Photodynamic therapy (PDT) consists of interaction between a photosensitizer, light, and oxygen, resulting in the production of reactive oxygen species, which leads to targeted cell death.
The two main topical photosensitizer prodrugs approved by the U.S. Food and Drug Administration (FDA) in the United States are 5-aminolevulinic acid (ALA) and its methylated derivative, methyl aminolevulinate (MAL).
PDT is a safe and effective treatment methodology that is commonly used for actinic keratosis (AK), actinic cheilitis, and superficial nonmelanoma skin cancers.
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DON’T FORGET
PDT is FDA approved in the United States for the treatment of AK and in the European Union for the treatment of AK, squamous cell carcinoma in situ, and superficial basal cell carcinoma.
ALA is available in two different formulations: a 20% cream, Levulan®, and a 10% gel, BF200-Ameluz®. MAL is available as a 16.8% cream, Metvix®/Metvixia®.
Multiple treatment protocols exist for various light sources in combination with different photosensitizer preparations.
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CLINICAL PEARLS
PDT can be used as an efficient therapy in field cancerization as monotherapy or in combination with other treatment modalities.
The management of pain and the phototoxic effects associated with PDT is important for patient satisfaction. Daylight PDT is a nearly pain-free and practical option for the treatment of AK.
Various pretreatment protocols have been shown to improve PDT efficacy. The use of fractional lasers before PDT treatment has been demonstrated to increase PDT efficacy in all settings.
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PATIENT EDUCATION POINTS
History of porphyria, photosensitizing disorders, pregnancy, and allergy to ALA or MAL are the main contraindications to treatment. Exercising caution is warranted when the treatment is applied at the same time as other photosensitizing medications.
Patients should be instructed to remain indoors, 6 feet away from any window, and to avoid outdoor sunlight exposure or intense indoor light for 36 hours after the procedure. Mineral-based and physical sunblock may not be enough during this period because most do not block visible light effectively.
Erythema, edema, and transient pigmentary changes are common after treatment and may last up to 2 weeks.
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Photodynamic therapy (PDT) consists of the interaction between a photosensitizer and light in the presence of oxygen, resulting in the production of reactive oxygen species, which leads to targeted cell death with minimal effect on the surrounding tissues. Mainstream use of PDT started in the 1990s with the discovery of topical photosensitizers, but its formal history dates back almost a century to the experiments that led to the development of agents used today. The two main topical photosensitizer prodrugs are 5-aminolevulinic acid (ALA) and its methylated derivative, methyl aminolevulinic acid (MAL), both of which lead to the production of protoporphyrin IX (PpIX) once absorbed in the tissue. PDT is a safe and effective treatment option for the treatment of actinic keratosis (AK) and superficial nonmelanoma skin cancers (NMSCs).
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