[Mixed adenoneuroendocrine carcinoma with multiple liver metastases successfully treated by cetuximab/CPT-11 chemotherapy followed by curative resection - a case report].

A 73-year-old man underwent laparoscopy-assisted partial resection of the rectum to treat rectal cancer diagnosed in September 2011 at a previous hospital. Lymph node dissection was not performed and the vertical margin was positive. When multiple liver tumors were detected 10 months later, the patient was referred to our hospital. A computed tomography (CT) scan revealed local recurrence of the rectal cancer, lymph node metastasis, and 9 liver metastases, which had a maximum diameter of 10 cm, and where curative resection would have been difficult. The rectal cancer expressed epidermal growth factor receptor (EGFR) and wild type K-ras gene, and we initiated cetuximab/irinotecan (CPT-11) chemotherapy. After 2 courses of chemotherapy, the liver tumors had markedly decreased in size and anterior resection of the rectum with regional lymph node dissection was performed. The pathological diagnosis of the rectal tumor was mixed adenoneuroendocrine carcinoma ( MANEC). Extended right hepatectomy was performed four months later. The liver tumors were also diagnosed as metastases of MANEC of the rectum. The therapeutic efficacy of chemotherapy was assessed as Grade 1b. The patient is alive without recurrence 34 months since the initial rectal surgery and 15 months after the liver resection. Thus, an anti-EGFR antibody agent might be effective against MANEC of the colon and rectum.