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.