Efficacy and safety of topical SR-T100 gel in treating actinic keratosis in Taiwan: A Phase III randomized double-blind vehicle-controlled parallel trial

Actinic keratosis (AK) is the precursor lesion of cutaneous squamous cell carcinoma (SCC) and displays squamous cell dysplasia confined to the epidermis [1]. AK is exceedingly common in the skin of elderly Caucasians who have chronic exposure to sunlight [2–4]. The actual risk regarding progression from AK to invasive SCC for specific individual lesions is not known, but is estimated to be approximately 0.25–20% per year [5]. Remarkably, up to 60% of invasive SCC was derived from AK [6]. Therefore, the current treatment consensus recommends eradication of all AK when detected clinically [5,7,8].