The Evolution of Staging of Cutaneous Squamous Cell Carcinomas: A Structured Review

Among non-melanoma skin cancers, cutaneous squamous cell carcinoma entails the highest morbidity and mortality, and yet there is little guidance on how to identify the subset of cutaneous squamous cell carcinomas that behave aggressively. The staging of non-melanoma skin cancers is meant to provide this guidance, by dividing patients into groups for which survival differs between groups, is similar within each group, and consistently decreases with each increasing stage group. In the present review, we explore the history of how the staging of non-melanoma skin cancers, focusing on cutaneous squamous cell carcinomas, has evolved over time. We describe the common criticisms leveled at the American Joint Committee on Cancer (AJCC) staging rubric. We discuss alternative staging systems that have recently been proposed, and how they have stood up to validation. Finally, we preview the AJCC staging changes that will go into effect next year and lay out some future directions for the improvement of skin cancer staging.