A rare case report on esophageal squamous cell carcinoma metastatic to the colon.

Esophageal squamous cell carcinoma(ESCC) carries a poor prognosis with low survival rates, frequently due to advanced disease at diagnosis. Colonic metastasis from ESCC is exceptionally rare. This report describes the case of a 68-year-old male with locally advanced ESCC who developed metachronous colonic metastasis during follow-up after initial definitive chemoradiotherapy combined with immunotherapy. Pathological examination of a colonic biopsy confirmed metastatic squamous cell carcinoma with an immunohistochemical profile consistent with esophageal origin. The patient subsequently received systemic chemotherapy followed by combined immunotherapy, achieving a partial response on imaging evaluation. This case not only underscores the rarity of colonic metastasis in ESCC but also highlights the critical importance of maintaining vigilance for this possibility within multidisciplinary care and long-term follow-up.