Clearance rates for actinic keratoses (AKs) on the extremities were prolonged by adding thermal modulation to photodynamic therapy (PDT), a study has shown.
The single-site study of 17 adults with 10 or more AKs on their arms or legs evaluated thermally modulated PDT: 20% 5-aminolevulinic acid (ALA) applied to skin, occluded with plastic wrap and warmed with an electric heating pad to a median 41.2° C for one hour, then exposed to blue light. Treatment resulted in 90% clearance rates at 3 months and 12 months, reported Dr. Andrea Willey, a dermatologist in Sacramento, Calif., and her associates (Dermatol Surg. 2015 Nov;41[11]:1290-5).
They were inspired to conduct the study as a follow-on to a recently published pilot study of three patients, which found that clearance rates of AKs on the arm treated with thermally modulated 5-ALA blue light PDT persisted up to 14 months after treatment, when compared with the control arm, which was not heated.
In their study, there were 724 grade 1 and 2 AKs at baseline – a median of 15 per extremity; patients were followed up at 3, 6, 9, and 12 months. The total lesion count across the entire cohort was 70 at 3 months, 69 at 6 months, 64 at 9 months, and 72 at 1 year. No new AKs were seen in the treated areas during the 1-year follow-up.
There were 13 grade 3 hypertrophic AK lesions among all study participants. Although these lesions persisted, Dr. Willey and her coauthors noted that they did shrink initially after treatment.
Adverse events associated with the combination therapy were low, and included mild erythema and crusting up to 1 week post treatment, indicating the therapy was well tolerated, and patient satisfaction was high.
The results “suggest that mild skin warming may both improve efficacy and reduce variability of response to PDT in practice,” the authors wrote.
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