SONOMA, CALIF. – Combining lesional and field therapy may be the most effective way to treat actinic keratoses, Dr. David Pariser said at the annual Coastal Dermatology Symposium.
Because there’s no way to tell which actinic keratoses will progress to invasive squamous cell carcinoma, it’s reasonable to treat all lesions, said Dr. Pariser of Eastern Virginia Medical School, Norfolk, Va.
Studies comparing field versus lesional therapy to treat grade 1 and 2 lesions that were minimally or moderately thick found better long-term efficacy rates and better sustained clearance with field therapy, he said.
Dr. Pariser said he tends to treat actinic keratoses first with field therapy using photodynamic therapy or a topical agent, “then clean up what’s left with cryotherapy.”
Dr. David M. Pariser
Field therapy options include topical agents, laser ablation, or photodynamic therapy. Lesion-targeted therapies include cryosurgery, curettage, electrosurgery, or photodynamic therapy. Cryotherapy was the third most effective treatment in a review of the literature, he noted, after photodynamic therapies.
“None of these” other treatments “are going to put us out of the cryotherapy business,” Dr. Pariser said, “The best reimbursement is for cryotherapy, but the best way today is to do both” targeted and field therapy, he said at the symposium, jointly presented by the University of Louisville, Ky. and the Global Academy for Medical Education. This news organization and the Global Academy for Medical Education are owned by the same parent company.
He summarized the efficacy of various treatments for actinic keratoses from data in trials comparing cryotherapy versus photodynamic therapy or imiquimod and for other therapies from data in randomized controlled trials or prescribing information.
Photodynamic therapy after application of the photosensitizing agent aminolevulinic acid (ALA-PDT) cured 89% of actinic keratoses, compared with 12% using vehicle only. Photodynamic therapy after application of the photosensitizing agent methylaminolevulinate (MAL-PDT) cured 82% of lesions, compared with 37% in the vehicle group. Cryotherapy cured 72% in the studies he reviewed.
“I like photodynamic therapy. The evidence is as strong as any other treatment,” and it causes less scarring than destructive modalities, but reimbursement issues have been an impediment to widespread acceptance of photodynamic therapy in the United States, Dr. Pariser said.
He tells patients that they’ll need two photodynamic therapy treatments, 4 weeks apart. Some patients have such a good response to the first treatment that they don’t need another treatment when they come for the second visit.
For actinic keratoses on the upper extremities, occluding the area during the incubation period following application of topical ALA significantly increased clearance rates in studies. “Just wrap it with (plastic wrap),” he suggested. Occlusion may increase efficacy by raising skin temperature, he speculated.
In a separate study, the results seen with incubating for 1 hour was as good as 2 or 3 hours. “Now, I incubate for 1 hour. In good conscience, I can tell patients it will work just as well,” he said. The study also found similar clearance rates using spot therapy or broad-area application, “which was surprising to me,” he added, but lesions that cleared after broad-area treatment were more likely to remain clear from week 12 to week 24, compared with lesions that received spot treatment.
Among topical agents, 5-fluorouracil or ingenol cleared 58% of actinic keratoses, compared with 2% or 4% of lesions treated by vehicle, respectively, in the studies Dr. Pariser reviewed. Diclofenac cleared 47%, compared with 19% in the vehicle groups, and imiquimod cleared 46%, compared with 3% in the vehicle groups.
Most patients treated with 5-fluorouracil will develop mild to moderate skin irritation. Lesion site reactions also are an issue with ingenol mebutate, “the newest kid on the block for actinic keratoses,” he said. “Tell patients it’s going to happen. Show them photos.”
Dr. Pariser reported having no financial disclosures.
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