Insulin-like growth factor II-producing metastatic colon cancer with recurrent hypoglycemia

A 45-year-old man was referred to our hospital and found to have a tubular adenocarcinoma of the descending colon with multiple liver metastases. During hospitalization, the patient suffered recurrent hypoglycemic attacks that required intravenous 50% glucose infusion. He was diagnosed with non-islet cell tumor hypoglycemia (NICTH) because the colon cancer tissue obtained by biopsy was strongly stained for insulin-like growth factor-II (IGF-II) by immunohistochemistry. He received chemotherapy with oxaliplatin, 5-FU and leucovorin (FOLFOX) plus bevacizumab (Bmab), and showed a partial response. As the metastatic lesions decreased in size, the hypoglycemic attacks gradually disappeared. Subsequently, he received outpatient chemotherapy and maintained a high quality of life for about 10 months. Western blot analysis of IGF-II in serum at the time of admission showed a high-molecular-weight form of IGF-II, which was considered to have caused hypoglycemia. This patient presents a very rare case of colorectal cancer associated with NICTH syndrome due to production of high-molecular-weight IGF-II by cancer cells. It is important to investigate IGF-II expression in cancer tissues for establishing the diagnosis of NICTH in cases with intractable hypoglycemia complicated by advanced cancer.