Clonal tracing of rare anal metastasis in esophageal squamous cell carcinoma: a case report with whole-exome sequencing and multimodal therapy.

Esophageal squamous cell carcinoma (ESCC) shows considerable variation in incidence across different regions and is affected by various risk factors, including smoking and HPV infection. This article presents a rare case of ESCC that metastasized to the anal region, illustrating the effectiveness of whole-exome sequencing and clonal evolution analysis in identifying the origins of the metastasis. The findings reveal distinct clonal characteristics between the primary tumor and the metastatic site. This underscores the importance of molecular profiling for developing effective treatment strategies.