The methyl ester derivative of ALA, known as Metvix, is available in Europe and several other countries, and is currently undergoing clinical evaluations in the United States. Many trials evaluating the methyl ester of ALA have been performed utilizing a red laser light source at 630 nm (Fig. 6.1). This approach led to Euro pean Union approval for the treatment of non-hyperkeratotic AKs of the face and scalp as well as BCCs which are unsuitable for conventional therapy. Recommendations for the use of the methyl-ALA include the gentle scraping or curettage of the effected lesion prior to the application of the methyl-ALA cream. This is then occluded for 3 h before the cream is removed and the area is subjected to the red laser light source. Several recent clinical trials support the use of the methyl-ALA in the treatment of AKs. In one study, investigators studied 204 individuals treated with the methyl-ALA cream as compared to cryotherapy and placebo. The methyl-ALA technique was found to have better response rates and cosmetic improvement compared to both cryotherapy and placebo. In another study, investigators studied the methyl-ALA cream in 80 individuals with AKs. They found an 89% improvement in the AKs and a 90% improvement in the cosmetic appearance. In their group of patients, 72% of them preferred PDT over both cryotherapy and 5-FU therapy. Others recently completed a prospective randomized study of BCCs treated with either methyl-ALA or surgery in 101 patients. After 3 months of follow-up, there was a 98% complete response rate with surgery versus a 91% response rate with the methyl-ALA. After 12 months, there was a 96% response rate with surgery and an 83% response seen in the methyl-ALA group. At 24 months, there was one recurrence noted in the surgery group and 5 in the methyl-ALA group. The authors concluded that the cosmetic appearance was better in the methyl-ALA group compared to the surgical group.
ALA-PDT is a new therapeutic modality to enhance previously accepted lasers and light source technologies. With short-contact, topical ALA full-face treatments, it appears that all parameters of photorejuvenation and associated AKs can be successfully treated with a reduced number of treatments. The exact number of required therapeutic sessions has yet to be determined. Most clinicians perform one to three sessions at 1-month intervals. Adverse events are kept to a minimum. Patients routinely report no downtime from day-to-day activities utilizing ALA-PDT in this manner. Further research is required to further validate and define this new therapy for photorejuvena-tion and associated AKs.
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