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Updated: Jun 23, 2026
An In Vitro Approach to Photodynamic Therapy
Published on: August 17, 2018
Short incubation with methyl aminolevulinate for photodynamic therapy of actinic keratoses
L R Braathen1, B E Paredes, O Saksela
1University Clinic for Dermatology, Inselspital, Bern CH-3010, Switzerland. lasse.r.braathen@bluewin.ch
Background:
Photodynamic therapy (PDT) using methyl aminolevulinate (MAL) is an effective first-line treatment for actinic keratoses. A reduced incubation period may have practical advantages.
Objective:
This study aims to evaluate the effect of incubation time (1 vs. 3 h), MAL concentration (160 mg/g vs. 80 mg/g) and lesion preparation in the setting of MAL-PDT for treatment of actinic keratosis (AK).
Design:
Open, randomized, parallel-group multicentre study.
Setting:
Outpatient dermatology clinics.
Subjects:
One hundred and twelve patients with 384 previously untreated AK. Most lesions (87%) were located on the face and scalp and were thin (55%) or moderately thick (34%).
Methods:
Lesions were debrided, and MAL cream (160 mg/g or 80 mg/g) was applied before illumination with red light (570-670 nm; light dose, 75 J/cm2). Patients were followed up at 2 and 3 months. Sixty patients (54%) were re-treated and assessed at 6 months.
Main Outcome:
Complete lesion response rates 3 and 12 months after last treatment.
Results:
For lesions on the face/scalp, lesion complete response rates were 78% for thin AK and 74% for moderately thick AK lesions after 1 h vs. 96% and 87% after 3 h incubation with MAL 160 mg/g. Lesion recurrence rates at 12 months after two treatments were similar [19% (3 of 16) with 1 h vs. 17% (3 of 18) with 3 h 160 mg/kg MAL-PDT] and lower than for 80 mg/g MAL-PDT (44-45%).
Conclusion:
MAL-PDT using a 1-h incubation may be sufficient for successful treatment of selected AK lesions.
