RESUMEN
OBJECTIVE: Photodynamic therapy (PDT) is an effective treatment against skin field cancerization. Its main side effect is local inflammation in the treated area. The phenolic compound oleocanthal (decarboxy methyl ligstroside aglycone), which is present in extra virgin olive oil (EVOO), has anti-inflammatory properties. The purpose of this study was to evaluate the topical efficacy of an oily fluid enriched with oleocanthal (OC) extract, in comparison with a conventional oily fluid, in reducing the degree of inflammatory reaction after conventional PDT. METHODS: Quasi-experimental pilot study, before-after with a control group, performed with a cohort of consecutive patients diagnosed with actinic keratosis/field cancerization (AK/FC) in the forehead and/or scalp, treated by PDT. The study was carried out from April 2016 to November 2017 at a speciality hospital in southern Spain. A group of 24 consecutive patients received the topical application, three times daily for one week, of an emollient oily fluid in the area treated with PDT. Subsequently, another group, of 23 consecutive patients, received the same treatment pattern with an oily fluid enriched with OC extract. The post-PDT inflammatory reaction was measured by an independent member of the hospital's dermatology department, using the following visual scale of erythema (from 0 to 4).The assessment was conducted at 30 min and at 48 h post-PDT. RESULTS: In the assessment at 48 h after treatment, the inflammation had improved more among the patients treated with OC (median: 25%, 95%CI: -5.3 to 28.5) than in the non-OC group (median: 0%; 95%CI: -45.2 to -6.2). The difference was statistically significant (p<0.01), and the Cohen's d value was 0.89 (large effect). At three months after PDT, a complete response had been obtained by 60.9% of the patients treated with OC compared to 29.2% of the non-OC group, and the difference was close to statistical significance (p=0.059). CONCLUSIONS: The topical application of an oily fluid enriched with OC extract achieved a greater reduction in post-PDT cutaneous inflammation and a better treatment response, in comparison with the application of a conventional oily fluid.