Photodynamic therapy ( PDT ) is an attractive therapy for nonmelanoma skin cancers and actinic keratoses ( AKs ).
Daylight-mediated photodynamic therapy is a simple and tolerable treatment procedure for PDT. Methyl aminolaevulinate ( MAL )-PDT is approved for the treatment of thin or nonhyperkeratotic actinic keratoses on the face and scalp. However, thick actinic keratosis lesions are often treated as well when present in the field-cancerized treatment area.
In a randomized multicentre study to evaluate efficacy of daylight-mediated PDT for different severity grades of actinic keratoses.
One hundred and forty-five patients with a total of 2768 actinic keratoses ( severity grades I-III ) of the face and scalp were randomized to either 1½ or 2½ h exposure groups.
After application of a sunscreen ( sun protection factor 20 ) and gentle lesion preparation, MAL was applied to the entire treatment area.
Patients left the clinic immediately after application and exposed themselves to daylight according to randomization.
Daylight exposure was monitored with a wrist-borne dosimeter.
No difference in lesion response was found between the 1½ and 2½ h exposure group.
The mean lesion response rate was significantly higher in grade I lesions ( 75.9% ) than in grade II ( 61.2% ) and grade III ( 49.1% ) lesions ( P less than 0.0001 ).
Most grade II ( 86% ) and III actinic keratoses ( 94% ) were in complete response or reduced to a lower lesion grade at follow-up.
Large variations in response rate of grade II and III actinic keratoses were found between centres.
No association was found between response rate and light dose in patients who received an effective light dose of more than 3.5 J cm(-2).
In conclusion, daylight-mediated photodynamic therapy of moderate to thick actinic keratoses was less effective than daylight-mediated photodynamic therapy of thin actinic keratoses especially in some centres.
However, nearly all thicker lesions ( grades II and III ) were reduced to a lower lesion grade at 3 months after a single treatment of daylight-mediated photodynamic therapy. ( Xagena )
Wiegell SR et al, Br J Dermatol 2012;166:1327-1332