Microwave Energy for Treatment of Superficial and in situ Squamous Cell Carcinoma

Synopsis

Localized, superficial microwave energy (ME) appears to have promise as a novel, rapid, and tolerated non-invasive approach to induce localized hyperthermic conditions for treating cutaneous non-melanoma skin cancers (NMSCs). Squamous cell carcinoma in situ (SCCis) is a very common NMSC appearing on sun exposed skin including the face. Standard treatments include excision or electrodessication and curettage, but other minimally invasive treatments are desirable, especially for areas with aesthetic importance, like the face, or regions that are slow to heal, such as the lower legs. Hyperthermia, a non-invasive treatment that raises tissue temperature above 43 degrees Celsius, has a long history in treating various cancers. Traditional hyperthermic treatments require warming large areas of tissue, but new technology now permits focused application of microwave energy (ME) to generate precisely targeted hyperthermic conditions in treated tissues. Literature suggests that localized hyperthermia increases tumor cell immunogenicity by activating stress response pathways in proliferative keratinocytes, promoting lesion clearance through innate and adaptive immune responses as well as apoptosis. Currently, both actinic keratoses (AKs) and human papillomavirus (HPV)-induced warts have been successfully treated with site-specific ME-induced hyperthermia. Given the higher incidence of SCCis in individuals with actinic damage and the evidence that ME can clear AK and hypertrophic AK (early stages in the squamous neoplasia continuum), increasing tumor immunogenicity via localized ME-induced hyperthermia may explain the observed clearance of cutaneous SCC (cSCC) lesions in the treated patients presented here. This feasibility work represents the first exploratory step in determining if ME-induced hyperthermia can serve as a novel, non-invasive treatment for NMSCs.

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