Cutaneous squamous cell carcinoma (cSCC) is economically a major burden to the NHS. The incidence is rising rapidly, with approximately 30,000 new cases per year in the UK. Immunosuppressed organ transplant recipients (OTR) have a more than 100-fold increased risk and an accelerated carcinogenic process, making them an ideal population in which to test interventions aimed at preventing cSCC. Premalignant lesions, termed actinic keratoses (AK), are present on sun-damaged skin and effective topical agents are available to treat them. The close relationship between AK and cSCC means that such topical treatment of a field bearing multiple AK should significantly reduce subsequent risk of developing cSCC, but this assumption has never been proven. The main objective of the study is thus to determine the feasibility of performing a larger phase III randomised controlled trial using topical treatment of AK as a strategy for prevention of invasive cSCC. The decision to perform a phase III ra