Actinic keratoses (AK) are common skin lesions caused by cumulative sun exposure. Since AK may progress to invasive cutaneous squamous cell carcinoma (cSCC), the guidelines uniformly recommend early and consequent treatment. 

Various interventions are known; however, most randomized controlled trials, meta-analyses and guidelines highlight outcomes usually evaluated 8 to 12 weeks after the end of treatment. Notably, these assessments capture the short-term, transient outcomes but escape drawing long-term results and reflecting the possibility of transition towards cSCC. 

To date, few studies have evaluated the long-term results of interventions for AK. Undoubtedly, discovering the most appropriate end-point and adjunct time point for determining the long-term results of interventions for AK is still a challenge. 

A recent study:

• Explains the different ways of measuring the efficacy of AK treatments, like using recurrence or sustained clearance rates, and discusses the methodological aspects.
• Highlights the importance of evidence from post-marketing surveillance trials for detecting efficacy values and safety signals.
• Emphasizes that a follow-up period of 12 months might not be sufficient to reflect the long-term results.
• Stresses the urgent need for a more extended follow-up period and regular risk-stratified surveillance.
• Emphasizes that longer follow-up is beneficial for obtaining long-term results. 

Furthermore, it also underlines the nonfeasibility and noncost-effectiveness of longer follow-up from a practical perspective, given the low transformation rate of AK into cSCC in most patients. Thus, explaining the importance of identifying patients at increased risk for transforming AK into cSCC. 

Source: Steeb T, Wessely A, Petzold A, et al. How to assess the efficacy of interventions for actinic keratosis? A review with a focus on long-term results. J Clin Med. 2021;10(20):4736.