A combination of short incubation and blue light followed by daylight exposure is a practical and feasible option for patients with actinic keratoses, researchers reported in a study published the Journal of the American Academy of Dermatology.

The randomized, single-blind trial sought to determine the tolerability and safety of daylight photodynamic therapy (PDT) for actinic keratoses on the face and scalp in patients living in northern California. Participants with 4 to 20 face and scalp actinic keratoses were randomly assigned (1:1:1) to 3 treatment groups and received topical application of aminolevulinic acid HCl solution 20%.

Group A underwent conventional treatment of 1 hour of incubation and 16 minutes 40 seconds of 417 nm BLU-U® Blue Light Photodynamic Therapy Illuminator. Group B received a combination therapy of 15 minutes of incubation, 16 minutes 40 seconds of BLU-U, and 45 minutes of daylight. Group C received daylight therapy of 15 minutes of incubation and 1 hour of daylight. A spectroradiometer was used to measure irradiance.

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The primary end point was tolerability, which was measured by patient-reported pain and blinded assessment of local skin reaction (LSR). Any adverse event (AE), 1 or more serious AEs, and AEs leading to early termination served as safety end points. The secondary end point was efficacy, measured via actinic keratosis clearance.

A total of 24 White men underwent treatment for actinic keratoses (17 face, 7 scalp). Participants’ mean age was 75 years (range, 60-94), and their mean baseline actinic keratoses count was 10.8 ± 4.9, similar in all groups. In the conventional group 1 participant discontinued treatment secondary to pain, and in the daylight group 1 participant was lost to follow-up.

The researchers found that peak pain was lower during treatment in the combination and daylight groups compared with the conventional group, with a difference of –3.4 (95% CI –4.44 to –2.30, P < .0001) and –3.5 (95% CI –4.57 to –2.42, P < .0001). Pain remained lower in these groups compared with the conventional group, with a difference of –1.8 (95% CI –2.95 to –0.80, P = .0007) and –1.8 (95% CI –2.98 to –0.76, P = .0011), they recorded. The composite LSR score peaked on day 8 for all groups and was significantly higher in the combination group compared with the conventional group (+2.13, 95% CI 0.64-3.61, P = .005).

The most frequent application site AEs were found to be pruritus (42%), burning/pain (38%), scaling (25%), and erythema (25%). The investigators observed 4 grade 2 AEs and no AE-related discontinuations. Mean actinic keratosis reductions were 63.9% ± 24.9, 66.4% ± 29.5, and 61.8% ± 59.9 for the conventional, combination, and daylight groups at day 84.

Daylight and combination PDT had lower overall and peak pain, but day 8 LSR was higher for the combination group compared with the conventional treatment group.

“This may be due to illumination with both blue light and daylight,” stated the researchers. “The study, though not powered to detect statistically significant differences in treatment efficacies, demonstrated efficacy similar to historical controls.”

Actinic keratoses clearance did not correlate with daylight solar irradiance (range, 8.5-1122.0 W/m2), the researchers noted.

“To maximize the safety of daylight PDT, providers should emphasize avoidance of light exposure following treatment,” the study authors concluded. “Daylight and combination PDT have a safety profile similar to conventional PDT. The combination regimen of short incubation and blue light followed by daylight exposure is a practical and feasible option.”

Disclosures: This study was sponsored by SUN Pharma/DUSA. Several of the authors reported affiliations with pharmaceutical, biotechnology, and other medical-related companies. Please see the original reference for a full list of authors’ disclosures.


Crow LD, Saylor D, Griffith-Bauer K, et al. Comparative tolerability and efficacy of daylight, conventional, and combination aminolevulinic-acid-photodynamic therapy for treatment of actinic keratosis. J Am Acad Dermatol. Published online January 19, 2021. doi: 10.1016/j.jaad.2021.01.031