PHOTODYNAMIC TREATMENT WITH NANOEMULSIFIED 5-AMINOLEVULINIC ACID AND NARROW BAND RED LIGHT FOR FIELD CANCERIZATION DUE TO OCCUPATIONAL EXPOSURE TO ULTRAVIOLET LIGHT IRRADIATION.

Actinic keratosis (AK) is a premalignant epithelial disease that develops on skin chronically exposed to ultraviolet-light. For outdoor workers, AK is an occupational hazard with a potential for malignant transformation into squamous cell carcinoma. Various topical treatments are used to treat AK's. Photodynamic therapy (PDT) promises the highest cure rates. We performed a prospective single center trial evaluating effects of PDT treatment for field cancerization due to occupational exposure to ultraviolet light irradiation in patients unresponsive to the treatment regimen with topical diclofenac gel. For PDT, a nanoemulsified 5-aminolevulinic acid (5-ALA) formulation was combined with narrow band red light irradiation with a peak wavelength of 635 nm and a total light intensity of 37 J/cm2. Clearance rate and adverse events were recorded. Thirty patients with a mean age of 77±10.5 years (26 males and 4 females) were included in the trial. They received between one and nine PDT sessions. Mean pain during PDT was scored at 6.8±2.8 using the visual analogue scale. Patients exhibited a mild immediate erythema after PDT. Among the patients, who tolerated PDT, a complete clearance was achieved in 93.3%, and >90% clearance - in 6.7%. Pain management was performed by cold-air analgesia. In conclusion, PDT with nanoemulsified 5-ALA and narrow band red light irradiation is an effective and safe treatment for occupational field cancerization without systemic toxicity. Adherence to this treatment is much better than to topical treatment.