Overcoming seasonability of treatment in actinic keratosis: clinical practice with 4% 5-fluorouracil

Background: Inflammation is a common feature of both actinic keratosis and its treatments, so that interventions are often avoided during the summer period, when the sun damage is more likely. 4% 5-fluorouracil cream is known to markedly attenuate local reactions compared to 5% 5-fluorouracil cream. Our aims were to compare the effects of AK treatment in summer and winter months. Methods: Our trial evaluated the tolerability levels of 4% 5-fluorouracil during the summer and winter periods in two groups of patients affected by actinic keratosis Olsen grade I and II. Evaluation of tolerability was performed by four specific questionnaires after four weeks of treatment with 4% 5-fluorouracil and a specific sunscreen, both once-daily, in summer months, and only 4% 5-fluorouracil once a day in winter months. We also objectively evaluated the effects of treatment with a visual instrument (VISIA) at the end of the treatment and after 3 months. Results: The main results were an attenuation of the worsening of the quality of life and the perception of the disease during the summer period compared to the winter months. The intensity of the symptoms has not worsened either and, in some cases, has even decreased in the summer group. Conclusions: Despite several limitations, this trial indicates that the treatment of actinic keratosis with 4% 5-fluorouracil together to the most suitable sunscreen can be performed with confidence even in the summer period.