Poor Outcome of Metastatic Cutaneous Squamous Cell Carcinoma: A Swedish Retrospective Study

The incidence of cutaneous squamous cell carcinoma is increasing rapidly, and 1.5-5% of cases develop metastatic disease, which is associated with a markedly worse prognosis. This study aimed to describe the characteristics of the primary tumour, the patients, and the metastases, as well as treatment and outcomes in patients with metastatic cutaneous squamous cell carcinoma. A total of 137 patients with a diagnosis of metastatic cutaneous squamous cell carcinoma within the Stockholm region during 2012-2020 were identified and included. Median age was 81; 79% were male; 70% had a WHO performance status of 0-1. 50% of the primary tumours were classified as high-risk tumours according to the Brigham and Women's Hospital system. The median time between diagnosis of the primary tumour and the diagnosis of regional metastases was 7 months and 90% of the metastases were diagnosed within 2 years. Most patients were treated with a combination of surgery and radiotherapy. Overall survival at 2 years was 56%. This study shows that metastatic cutaneous squamous cell carcinoma occurs in elderly but otherwise generally healthy patients, that primary tumours with a high risk of causing metastases seem hard to identify, and that metastases occur within 2 years after primary tumour diagnosis. The patient group overall has a high mortality rate, particularly among those who do not undergo surgery.