Large-cell carcinoma of the lung with a remarkable preoperative elevation of serum carcinoembryonic antigen level.

Carcinoembryonic antigen, a serum tumor marker, is useful for diagnosing cancer and for following the response to therapy in cancer cases. Serum carcinoembryonic antigen levels are also important as a predictive tool in evaluating prognosis. A 56-year-old man presented with an abnormal shadow on a chest X-ray. His preoperative serum carcinoembryonic antigen was at an elevated level of 1274.0 ng/ml. Chest computed tomography revealed a tumor in the posterior segment of the right lung and a swollen right interlobar lymph node. Right lung pneumonectomy and node dissection were performed. A histological diagnosis determined that the tumor was a large-cell carcinoma at clinical stage IIA. Immunohistochemical analysis detected the production of carcinoembryonic antigen by the tumor cells. Following surgery, the patient's carcinoembryonic antigen levels were maintained within the normal range. This is a rare case of lung cancer with no evidence of recurrence and metastasis for 8 years despite markedly elevated preoperative carcinoembryonic antigen levels.