A feasibility study of microwave therapy for precancerous actinic keratosis

Abstract

Summary Background Actinic keratosis (AK) is a common premalignant skin lesion that can progress to cutaneous squamous cell carcinoma (cSCC). Microwave therapy is an established cancer treatment and has been used for plantar viral warts. Objectives To evaluate the efficacy and feasibility of microwave as a treatment for AK. Methods Stage I was a dose‐setting study, in which seven participants had the dielectric properties of 12 thick and 22 thin AKs assessed for optimization of the microwave dose used for treatment in Stage II. Stage II was a randomized, internally controlled trial evaluating 179 AKs in 11 patients (93 treated, 86 untreated controls) on the scalp/forehead or dorsal hand. Participants received one treatment initially and a repeat treatment to unresolved AKs at week 4. The response was assessed at six visits over 4 months. The primary outcome was partial or complete resolution of the treated AKs. Results A significantly higher proportion of treated AK areas responded than untreated (90% vs. 15%; P < 0·001). Thin AKs were more responsive than thick AKs. The site did not affect efficacy. Pain was severe, but brief (80% reported pain lasting ‘a few seconds only’). Adverse effects were minimal (erythema, n = 6; flaking, n = 3; itch, n = 3). All participants who would chose microwave therapy over their current treatment cited the shorter discomfort period. Conclusions Microwave therapy is a portable, safe and effective treatment for AK. An easy‐to‐deliver, acceptable therapy for AK is attractive as a prevention strategy. While these results are promising, a larger randomized controlled trial is needed against an effective comparator to confirm clinical efficacy and patient acceptability. What is already known about this topic? Actinic keratoses (AKs) are common precancerous skin lesions. Successful treatment of AK can prevent cutaneous squamous cell carcinoma (cSCC). Most topical therapies for AK require repeated application over weeks and drive local skin inflammation, leading to poor compliance. An easy‐to‐deliver and effective treatment for AK, suitable for use in primary care, could reduce cSCC. What does this study add? Microwave therapy is a feasible, effective treatment for AK. Ninety per cent of treated AKs showed full or partial resolution at 120 days post‐treatment. Microwave therapy was painful, but the pain was short‐lived (seconds) and this short discomfort period was cited as the main reason that microwave was preferred to their current treatment. Linked Comment: Samimi and Kelleners-Smeets. Br J Dermatol 2020; 183:197–199.

Applications of Microwave Energy in Medicine

“…When in vitro- grown tumours were exposed to microwaves for 10 s both tumour cell death and a reduction in E6 and E7 in the treated zone and transition zone were observed. This reduction suggests that microwave interactions can reverse the cancerous phenotype caused by HPV; and that once an effective and proven method is developed it could provide a less invasive treatment for HPV benign tumours [ 57 , 58 ].…”

La QUERATOSIS ACTÍNICA Y SUS TRATAMIENTOS EN LOS ÚLTIMOS 4 AÑOS: UNA REVISIÓN.

“…Los pacientes que optaron por esta terapia mencionaron que era debido a su corto periodo de dolor. 32 También se han desarrollado cremas dermatológicas con función protectora y reparadora de daño solar. Es una buena opción a nivel de atención primaria.…”

Innovative devices for actinic keratoses: a hot‐button issue

“…In this issue of the BJD , Jackson et al . report a first‐in‐human study of an innovative lesion‐directed treatment of AK by a CE‐marked microwave medical device . Basically, microwaves fall in the range of the electromagnetic spectrum and deliver heat energy to induce an ablative destructive or subablative nondestructive effect on targeted lesions.…”

“…Overall, 90% of treated AKs showed full or partial resolution at 120 days post‐treatment. According to the authors, partial resolution of AK was related to the size of the applicator of the device; the clearance of AK was observed within the field of application of microwaves (6 mm in diameter) but not in the region that exceeded this area …”

“…Microwave therapy could play a role in the large variety of AK treatments. As such, the pain generated by the use of the microwave device was short‐lived and patients usually preferred microwave treatment to their current treatment . Another important issue is the practicality of the device, especially in the setting of primary care, as general practitioners (GPs) are involved in the medical care of patients with AK and lesion‐directed therapy by liquid nitrogen was previously reported as the main treatment modality in this setting .…”