Alpha-fetoprotein-producing Colon Carcinoma with Rapidly Increasing Liver Metastases That Resulted in Death: A Case Report.

Alpha-fetoprotein (AFP) has been widely used as a tumor marker for detecting hepatocellular carcinoma and yolk sac tumors. Recently, cases of gastrointestinal cancer with elevated serum AFP levels have been reported. However, AFP-producing colon cancer is considered rarer than other AFP-producing gastrointestinal cancers. In this study, we report on a case of a 47-year-old woman who was diagnosed with sigmoid colon cancer and underwent sigmoidectomy and lymph node dissection. Postoperative adjuvant chemotherapy (AC) was performed after the curative surgery. After the seventh course of AC, multiple liver masses and enlarged systemic lymph nodes were detected; these were later diagnosed as liver metastases from sigmoid colon cancer. Laboratory examination revealed high AFP levels (14,657.8 ng/mL). After confirming the recurrence, her condition worsened rapidly, and she eventually died 8 months after the operation. Autopsy and histopathological findings showed that the liver mass was positive for AFP staining, but the sigmoid colon cancer tissue was not. We then determined that liver metastases of the colon cancer were more likely than germ cell carcinoma according to the clinical course and pathological findings. We assumed that colon cancer cells can rapidly expand by dedifferentiation, and we diagnosed AFP-producing colon cancer with liver metastases. Despite curative surgery and AC for AFP-producing colon cancer, the patient died of liver and systemic lymph node metastases.