Experience with chemotherapy for postoperative metastases of adenosquamous carcinoma of the esophagogastric junction and pathological study of its development

We report here a case of postoperative recurrent adenosquamous carcinoma (ASC) of the esophagogastric junction (EGJ) treated with S-1 therapy. A 79-year-old woman was diagnosed with carcinoma of the EGJ. Thoracoscopic subtotal esophagectomy was performed, and pathological examination revealed advanced ASC with lymph node metastasis. Five months after surgery, multiple lung metastases and multiple lymph node metastases were observed, and the patient was treated with S-1 monotherapy, which showed partial response and may be effective for advanced ASC of the EGJ. On the other hand, immunohistological analysis of the tumors showed a relatively wide range of areas that could differentiate into both adenocarcinoma and squamous cell carcinoma, suggesting that tumor cells with multidifferentiation potential, or at least the ability to differentiate into both adeno-epithelial and squamous epithelial cells, were the likely source of the tumors.