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Temperature modulation increased efficacy of photodynamic therapy for actinic keratosis

Warming the skin after applying topical 5-aminolevulinic acid for photodynamic therapy to treat actinic keratosis resulted in long-term efficacy, according to results of a 1-year follow-up study.

Researchers enrolled 20 patients with at least 10 actinic keratoses on the upper or lower extremities in a single-center study between Sept. 12 and Oct. 4, 2012. During an incubation period, 20% topical 5-amenolevulinic acid was applied to both extremities and heated, which was followed by exposure to 10 J/cm² 417-nm blue light.

The median baseline temperature for the treated extremities was 31.6° Celsius, while the median maximum temperature during the 1-hour incubation period was 41.2° Celsius. Lesions were photographed and counted at baseline, and at follow-up visits at 1 week, and 3, 6, 9 and 12 months following treatment. Adverse effects, including erythema, edema, stinging and crusting, were graded at 5 minutes and at 3, 6, 9 and 12 months after treatment.

Seventeen patients (38 extremities) completed the 1-year study. Baseline count of total number of lesions was 724 grade 1 and grade 2 actinic keratoses (median 15 on each extremity). At 3 months, the lesion count was 70 (9.6%) and at 12 months, 72 (9.9%). Treatment did not resolve the grade 3 actinic keratoses.

There was a 90% median clearance that was maintained at 1 year, with no new lesions formed in the treated areas. Treatment was well-tolerated by all patients.

“Acceptable tolerability and increased efficacy of thermally modulated [5-amenolevulinic acid] blue light PDT for the treatment of [actinic keratoses] on the extremities are reproducible and persisted for 1 year after a single treatment,” the researchers concluded. “No new [actinic keratosis] lesions formed in the treated area throughout the 1-year follow-up period.”  – by Bruce Thiel

Disclosure: The researchers report no relevant financial disclosures.