Daylight Photodynamic Therapy Protocol Using Methyl Aminolevulinate (MAL)
Daylight photodynamic therapy (PDT) with methyl aminolevulinate (MAL) cream is a highly effective and less painful alternative to conventional PDT for treating actinic keratoses, with the protocol involving application of sunscreen, MAL cream application without occlusion, and 2 hours of daylight exposure at temperatures above 10°C. 1
Standard Protocol for Daylight MAL-PDT
Pre-treatment Preparation
- Perform gentle lesion preparation by removing crusts and scales with gauze soaked in saline or mild curettage to roughen the surface of the lesion 2
- Apply a high-SPF sunscreen without mineral filters to the entire treatment area 15 minutes before MAL application 1
- This protects from UV damage while still allowing visible light to activate the photosensitizer
MAL Application and Daylight Exposure
- Apply MAL cream (160 mg/g) to the treatment area without occlusion 1
- Within 30 minutes after MAL application, patient should begin daylight exposure 1, 3
- Patient should remain outdoors for 2 hours in a comfortable area (can be in shade) 1, 3
- Ambient temperature should be above 10°C for patient comfort and optimal efficacy 1, 4
Post-treatment Care
- After daylight exposure, remove any remaining cream with gauze and saline 2
- Protect the treated area from light exposure for 48 hours following treatment 2
- Patient should wear a wide-brimmed hat or similar head covering when outdoors 2
Efficacy and Treatment Considerations
- Clearance rates of 70-89% are reported for mild to moderate actinic keratoses on face and scalp 1, 5
- Daylight PDT is significantly less painful than conventional PDT, with mean pain scores of 1.3 on a 10-point scale 3
- Weather conditions do not significantly impact efficacy, though higher temperatures may improve results 4
- Treatment can be performed from spring to fall in temperate climates (June to October in Nordic countries) 3
Important Clinical Pearls
- Patient Selection: Best for mild (grade 1) to moderate (grade 2) actinic keratoses on face and scalp 4
- Treatment Limitations: Less effective for thicker (grade 3) lesions compared to conventional PDT 4
- Advantages:
- Contraindications:
Follow-up and Retreatment
- Evaluate treatment response at 3 months 2, 4
- Consider retreatment for non-responding lesions
- Recurrence rate at 6 months is approximately 17% for cleared lesions 4
Daylight PDT represents an excellent treatment option for patients with multiple actinic keratoses, offering similar efficacy to conventional PDT but with significantly improved tolerability and patient convenience 5. The protocol is straightforward and can be easily implemented in clinical practice with minimal equipment requirements.