Longitudinal Study of Different Progression Patterns in High-Risk Cutaneous Squamous Cell Carcinoma.

BACKGROUND AND OBJECTIVE: Cutaneous squamous cell carcinoma (cSCC) is the second leading cause of skin cancer mortality in Europe. Few studies have analyzed the different pathways of this tumor progression in its natural history. The main objective of this study was to analyze the different metastatic and progression pathways and their temporal occurrence in the evolution of cSCC.

MATERIAL AND METHOD: We conducted a multicenter, retrospective, and observational study of consecutive high-risk sSCCs included in the SQUAMATA project.

RESULTS: A total of 222 out of the 1346 patients included relapsed. The most frequent route of progression was the lymphatic one (62.6%). A total of 20.2% of the cases with lymphatic progression developed distant metastases. Only 1 case (3.1%) of distant metastasis followed local recurrence without previous lymphatic metastasis. The median time to disease-related mortality was longer in patients who developed systemic metastases than in those who died of locoregional progression.

CONCLUSIONS: The mortality of patients with cSCC is mostly due to the regional progression of their lymphatic metastases. The appearance of distant metastases is practically always (96.9%) associated with previous lymphatic metastatic progression. Therefore, in the future, new studies will be needed to assess the regional management of cSCC in both surgical and adjuvant therapies.