High-risk cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer and its incidence has increased in recent decades. Most cSCCs are successfully treated by surgery, but local and distant metastases develop in approximately 5% of cases; this proportion is higher in certain forms of cSCC with high-risk factors, namely: tumor size >2cm, depth >2mm, Clark level ≥IV, perineural invasion, lymphovascular invasion, poor differentiation, certain histologic subtypes (desmoplastic or adenosquamous carcinoma, invasive Bowen disease, or a cSCC arising in areas of chronic inflammation), immunosuppression, human papillomavirus infection, high-risk anatomic location (pinna of the ear, labial mucosa), expression of certain tumor genes, and inadequate tumor resection. The latest TNM (tumor, lymph node, metastasis) classification of cSCC published by the American Joint Committee on Cancer (AJCC) in the seventh edition of its Cancer Staging Manual now incorporates several of these risk factors to improve disease staging. We review all the factors currently considered to be markers of poor prognosis in cSCC and analyze the new AJCC classification and the different treatment options for high-risk cSCC.