Methyl Aminolevulinate 8% and 16% Incubated by 1 and 3 for Actinic Keratoses Treatment

The objective of this protocol is to compare the efficacy of the topical application of MAL at concentrations of 8% and 16%, mediated by red light, as well as to evaluate the impact of different incubation times (1 or 3 hours) in the treatment of actinic keratoses on the face, with a 6-month follow-up. This parallel-arm, 6-month follow-up randomized controlled clinical trial will consist of 4 groups: G1 - Control Group - MAL 16% irradiated with 643nm and 75J/cm² and 3-hour incubation time (n=36), G2 - MAL 16% and 1-hour incubation (n=36), G3 - MAL 8% - 3 hours (n=36), and G4 - MAL 8% - 1 hour (n=36). The researcher conducting the collection and the participant will be blinded to the interventions. The primary outcome will be the complete remission of the lesion at 6 months. Secondary outcomes will include treatment success (75% reduction in the initial number of lesions), recurrence rate, emergence of SCC, incidence of adverse effects, and improvement in skin texture, wrinkles, and pigmentation using a validated scale. All outcomes will be assessed at 30 days, 3, and 6 months. Quality of life will be evaluated using the Actinic Keratosis Quality of Life questionnaire (AKQoL) at 6 months.

The multifocality of actinic keratosis, the unpredictability of lesion evolution with potential progression to squamous cell carcinoma (SCC), and the consequent risk of local extension and metastasis, alongside the recent development of new therapies, make the selection of a therapeutic regimen challenging. The increasing incidence associated economic costs, and impact on quality of life have fostered interest in studying protocols for treating this severe skin condition. The topical application of 16% methyl aminolevulinate (MAL) is well-established in the literature for its local therapeutic effects and ease of application. However, the high cost of medication, long incubation time, and adverse effects such as itching and burning in some patients limit the dissemination of this treatment. Studies are needed to test other protocols of this promising therapy to increase acceptance among patients and professionals. Therefore, the objective of this protocol is to compare the efficacy of the topical application of MAL at concentrations of 8% and 16%, mediated by red light, as well as to evaluate the impact of different incubation times (1 or 3 hours) in the treatment of actinic keratoses on the face, with a 6-month follow-up. This parallel-arm, 6-month follow-up randomized controlled clinical trial will consist of 4 groups: G1 - Control Group - MAL 16% irradiated with 643nm and 75J/cm² and 3-hour incubation time (n=36), G2 - MAL 16% and 1-hour incubation (n=36), G3 - MAL 8% - 3 hours (n=36), and G4 - MAL 8% - 1 hour (n=36). The researcher conducting the collection and the participant will be blinded to the interventions. The primary outcome will be the complete remission of the lesion at 6 months. Secondary outcomes will include treatment success (75% reduction in the initial number of lesions), recurrence rate, emergence of SCC, incidence of adverse effects, and improvement in skin texture, wrinkles, and pigmentation using a validated scale. All outcomes will be assessed at 30 days, 3, and 6 months. Quality of life will be assessed using the Actinic Keratosis Quality of Life questionnaire (AKQoL) at 6 months. If data are normal, they will be subjected to 3-way ANOVA and presented as means ± standard deviation (SD). Otherwise, they will be presented as median and interquartile range and compared using the Kruskall-Wallis and Friedman tests. Categorical variables will be evaluated with the chi-square test, Fisher's exact test, or likelihood ratio test. A p-value \< 0.05 will be considered significant.

Eligibility Criteria:
Inclusion Criteria:

* Individuals of both sexes,
* Aged between 40 and 90 years,
* Fitzpatrick skin phototypes I to IV,
* Photodamaged skin with at least five clinically evident actinic keratosis lesions on the face to be treated,
* No prior treatment for at least six months.

Exclusion Criteria:

* Clinically diagnosed infiltrative lesions, as the gold standard treatment is surgical with histopathological evaluation of the lesion (surgery will be performed at no cost to the participant), who will receive guidance and referral for appropriate treatment.
* Photosensitive diseases, such as systemic lupus erythematosus, dermatomyositis, porphyria, among others.
* History of arsenic exposure,
* Known allergy to MAL or similar photosensitizing agents,
* Psychoactive drug abuse,
* Previous radiotherapy at the lesion site(s),
* Participation in another clinical trial,
* Intense tanning at the time of treatment,
* Pregnant or breastfeeding women,
* Local or systemic infection,
* Immunosuppression: uncompensated chronic diseases or emotional disorders considered contraindications to treatment,
* Skin conditions on the neck and anterior chest.