Evaluation of Non-inferiority and Tolerability of the Device PHOS-ISTOS

This study aims to compare the efficacy and tolerance of a new photodynamic therapy device (PHOS-ISTOS) with the conventional PDT device (Aktilite®) for the treatment of actinic keratosis of the scalp

The study is an intraindividual comparison of two methods. The number of subjects to be enrolled is 47. Patients will receive both treatments in a single visit: A first period of 2.5 hours of illumination with Phos-Istos device followed by a continuous red light spectrum (between 7 and 10 minutes) with Aktilite® after an appropriate incubation of MAL (methyl aminolevulinate). Patients will complete a pain assessment scale after receiving both treatments. 3 follow-up visits will be then scheduled

Eligibility Criteria:
Inclusion Criteria:

* Clinical diagnosis of minimum 10 previously untreated not pigmented, non-hyperkeratotic AK lesions of Grade I and II of the forehead and/or scalp (according to Olsen et Al. JAAD 1991, cf. REF 31) where other therapies are unacceptable or considered medically less appropriate with a symmetrical repartition on both side of the forehead and/or scalp. The diagnosis of AK will be determined upon clinical evaluation (i.e. visual inspection and palpation) by the investigator.
* No treatment for the AKs in the previous 30 days.
* Symmetrical areas in terms of number and severity of lesions. The axis of symmetry between the two areas will be defined by the investigator according to the distribution of lesions.
* The two areas to be treated should not be coalescing. A minimum distance of 10 mm is required between the lesions located on the 2 symmetrical areas. A minimum distance of 2 mm is required between the lesions on the same side.
* Minimum 5 lesions with similar dimensions at both symmetrical areas will be treated. If the number of lesions is \>7, only 7 lesions on each side will be considered.

Exclusion Criteria:

* Patients with porphyria.
* Patients immunosuppressed for idiopathic, disease specific or therapeutic reasons.
* Use of topical corticosteroids to lesional areas within 2 weeks before PDT.
* Patients receiving local treatment (including cryotherapy and curettage-electrocoagulation, any PDT treatment) in face / scalp area within the last 30 days.
* Patients receiving topical treatment (including imiquimod, 5-FU and diclofenac, Picato) in face / scalp area within the last 30 days.in
* Use of topical retinoids or alpha-hydroxy acids, systemic retinoids, chemotherapy or immunotherapy within 30 days of PDT.
* Pigmented AK lesion(s).
* Known allergy to Metvixia/Metvix, a similar PDT compound or excipients of the cream including arachis oil, or to peanut or soya.
* Participation in other clinical studies either currently or within the last 30 days.
* Female subjects must be of either:

  * Non-childbearing potential, i.e. post-menopausal or have a confirmed clinical history of sterility (e.g. the subject is without a uterus) or,
  * Childbearing potential, provided there is a confirmed negative urine pregnancy test or blood analysis prior to study treatment, to rule out pregnancy.
* Any condition which may be associated with a risk of poor protocol compliance.
* Patients currently receiving regular ultraviolet radiation therapy.