Microwave Therapy for Treatment of Precancerous Actinic Keratoses

This study is a collaboration between the University of Dundee, NHS Tayside and Emblation Ltd, funded by Innovate UK. Emblation is a Scottish based Small Medium sized Enterprise (SME) and is an established global leader in the design, development and manufacture of microwave medical devices.

Actinic keratoses (AK) are believed the most common pre-cancerous lesions in humans and are precursors to invasive cutaneous squamous cell carcinoma (cSCC), a malignancy that has more than doubled in incidence in the UK in the last decade due to ageing populations and increased UV exposure (Goon 2017). The UK incidence of cSCC now exceeds 30,000 annually (estimated >50,000 cases/year, Public Health England, unpublished data) with significant health burden and NHS costs These skin cancers are often multiple, especially in immunosuppressed high-risk populations. AK are very common "sun damage" skin lesions found on sun-exposed areas of the skin, such as the backs of hands and bald scalp. Up to 70% of our elderly population have AK and 65% of cSCC arise from previously identified AK. AK are readily identified clinically so AK treatment offers an important opportunity for cancer prevention, but our ability to treat is limited by undesirable local adverse reactions from existing topical treatments which fail to balance effectiveness, side effects and cost. None of the currently available treatments for AK are suitable for widespread use in the community and are only partially effective. Other more effective treatments such as photodynamic therapy are expensive and time consuming and need to be delivered by experts in secondary care. NHS dermatologists are already overburdened and elderly patients with AK do not wish to travel. AK therapy would be greatly improved by a cheap, convenient, well-tolerated and efficacious therapy that can be delivered closer to home by General Practitioners (GPs) or nurses.

Clinically, AK display a spectrum of severity from mild Grade 1 lesions, which are just visible and just (barely) palpable, through Grade 2 red and scaly lesions (easily felt and seen), to the most severe Grade 3 lesions, which are grossly hyperkeratotic and "thickened" skin lesions. In practice, it is easier to grade them as 'thin' (just palpable) or 'thick' (with substance to them). It is possible that the dielectric properties of Thick and Thin AK will differ and therefore the measurement study will need to be carried out on both types of AK such that the appropriate microwave dose can be given to these variable skin lesions

The investigator's hypothesis is that localised microwave energy therapy is a suitable treatment for Actinic Keratosis (AK) skin lesions.

The use of microwave technology is well established as ablative doses for treatment of malignancy e.g. hepatocellular carcinoma. There are no known studies using microwave for treatment of pre-cancerous skin conditions or skin cancers. Furthermore, there is very little understanding of the biological process evoked by localised microwave exposure in the skin or of the clinically-relevant biological mechanisms triggered.