Cutaneous squamous cell carcinoma (CSCC) is the second most common form of skin cancer, and one of the most common cancers worldwide. The majority of CSCCs are easily removed by surgery and have excellent prognosis. However, a small subset has poor outcomes, including secondary spread in the body (metastasis) and death.

The investigators will look at existing CSCC in people from two UK dermatology centres. The investigators will then evaluate the accuracy of current staging systems in predicting risk of poor outcomes in people. The investigators hope that this project will improve the management of patients with CSCC by validating the predictive power of currently available histological staging classifications for cSCC. In the second stage of the study, The investigators will see whether better prediction tools can be found.

Inclusion Criteria:

• Over 18 years old with diagnosis of CSCC

Exclusion Criteria:

• Patients who decline for their data to be used for research purposes

Patients treated at two tertiary Dermatology centers