Only in tiny data sets have risk variables for cutaneous squamous cell carcinoma (cSCC) metastasis been studied. For a study, researchers sought to investigate and reproduce risk variables for metastatic cSCC. Metastatic patients were chosen from English and Dutch countrywide cancer registry cohorts and matched 1:1 to controls. The variables were derived from pathology reports obtained from England’s National Disease Registration Service. A dermatopathologist in the Netherlands reviewed histopathologic slides from the Dutch Pathology Registry. Backward conditional logistic regression was used to develop the model in the English data set, and replication was done in the Dutch data set. 

In addition to diameter and thickness, poor differentiation (odds ratio [OR], 4.56; 95% CI, 2.99-6.94), invasion in (OR, 1.69; 95% CI, 1.05-2.71)/beyond (OR, 4.43; 95% CI, 1.98-9.90) subcutaneous fat, male sex (OR, 2.59; 95% CI, 1.70-3.96), perineural/lymphovascular invasion (OR, 2.12; 95% CI, 1.21-3.71), and facial localization (OR, 1.57; 95% CI, 1.02-2.41). Nonlinear correlations between diameter and thickness and metastasis were found. In the Dutch data set (n=434 cSCCs), similar ORs were identified. Differentiation, clinical features such as gender and tumor location, and nonlinear connections for diameter and thickness can all help to enhance cSCC staging systems.