Reviewing the genetic alterations in high-risk cutaneous squamous cell carcinoma: a search for prognostic markers and therapeutic targets

Cutaneous squamous cell carcinoma (SCC) is second only in incidence to basal cell carcinoma (BCC), effecting up to 500 000 people in the United States annually. Metastasis to regional lymph nodes occurs in approximately 5% of cases and imparts significant morbidity. Standard treatment in this group involves a combination of surgery and adjuvant radiation. Currently, there are no clinically useful biomarkers of metastatic potential in primary cutaneous SCC and histological predictors can be unreliable. The high level of mutational burden in normal UV-exposed skin has hampered the search for novel drivers of invasive disease, and indeed metastatic potential. This review outlines the clinical problems in high-risk and metastatic cutaneous SCCs, reviews the known genetic events and molecular mechanisms in high-risk primary cutaneous SCC and metastasis, and identifies avenues for further investigation and potential therapy.