Response to chemotherapy in a case of gastric adenocarcinoma producing granulocyte colony-stimulating factor

Little is known about the patient characteristics and tumor characteristics associated with a high level of granulocyte colony-stimulating factor (G-CSF) and leukocytosis. Moreover, the prognosis of G-CSF-producing gastric cancer has been extremely poor.

A 72-year-old man presented with fatigue and body weight loss. Laboratory testing showed pronounced leukocytosis (white blood cell count, 34900×106/L). Bone marrow aspiration biopsy excluded leukemia and metastatic leukemoid reaction. G-CSF-producing cancer was suspected as the cause of the abnormally elevated serum G-CSF level (293 pg/ml). Gastrointestinal endoscopy showed type 3 gastric cancer, and the biopsy specimens were histologically proven to include moderately to well differentiated adenocarcinoma with positive expression of G-CSF. Abdominal computed tomography showed a lymph node lesion and multiple hepatic metastatic lesions. This patient was diagnosed as having stage IV gastric cancer that produced G-CSF. We treated the patient with 3 chemotherapy regimens, and he survived for almost 2 years after diagnosis.

The possibility of a G-CSF-producing tumor should be investigated in patients who present with severe leukocytosis in the absence of infection. This unusual gastric cancer should be treated as soon as possible after diagnosis.