Advanced and Metastatic Non-Melanoma Skin Cancer: Epidemiology, Risk Factors, Clinical Features, and Treatment Options.

Non-melanoma skin cancers (NMSC) form the majority of skin cancers, with basal cell carcinoma (BCC) being the most common and cutaneous squamous cell carcinoma (cSCC) being second. Prolonged ultraviolet (UV) exposure, aging, male gender, and immunosuppression represent most of the causes of this category of diseases. BCCs and cSCCs both include different types of skin cancers, such as nodular or morpheaform BCC or flat cSCC. Locally advanced and metastatic NMSCs cannot be treated surgically; thus, systemic therapy (TKI and Immunotherapy) is needed. Interestingly, NMSCs are frequently linked to abnormal Hedgehog (HH) signaling which most systemic immunotherapies for these cancers are based upon. Of note, the first line therapies of BCC, sonidegib and vismodegib, are HH inhibitors. Programmed death receptor 1 antibody (PD-1) inhibitors such as cemiplimab, pembrolizumab, and nivolumab have been approved for the treatment of cSCC. Thus, this paper reviews the epidemiology, risk factors, clinical features, and treatment options for both BCC and cSCC.