A large randomized, controlled, multicenter study reported similar clearance response rates following MAL-PDT (86%), single freeze-thaw cryotherapy (82%), and 1 month application of 5-fluorouracil (83%) in 225 patients with histologically confirmed Bowen's disease. MAL-PDT (MAL 3h, 75J/cm2, 570-670nm, 70-200mW/cm2) was given as a single cycle 1 week apart. Lesions with a partial response at 3 months were re-treated. Cosmetic outcome was superior for MAL-PDT in 94% of patients vs. 66% with cryotherapy, and 76% with fluorouracil. Clearance rates after 2 years for MAL-PDT was 68% vs. 60% with cryotherapy and 59% with fluorouracil.
MAL is an effective low molecular weight topical porphyrin-inducer that is typically used in combination with a red light-emitting diode for PDT. It offers therapeutic benefit for thin and moderate thickness AKs. It should be considered as a treatment option for superficial BCCs and Bowen's disease, particularly in situations where surgery may be problematic or where patients have multiple lesions. However, long-term cure rates, as mentioned above for Bowen's disease and sBCC, are only 68% and 75% respectively. Because of the appreciable nonresponse and recurrence rates, patients treated with PDT for either disease should be monitored closely during the first 2-3 years after PDT, which is when most lesion recurrences occur. According to studies, patients' high preference for MAL-PDT may be mainly due to its good to excellent cosmetic outcome and general tolerability of side-effects. No direct comparative studies have yet been reported with MAL and ALA. Important parameters, such as the depth of penetration of MAL-PDT, tumor thickness, location, and careful patient selection are key elements for efficacy. In the US, MAL-PDT is currently FDA-approved for the treatment of AKs only, whereas in Canada, MAL-PDT is officially indicated for the treatment of both AKs and sBCCs.
Skin Therapy Letter. 2009;14(6) © 2009 SkinCareGuide.com
Cite this: Methyl Aminolevulinate-PDT for Actinic Keratoses and Superficial Nonmelanoma Skin Cancers - Medscape - Jul 01, 2009.