The use of markers in pericardial fluid such as carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), carbohydrate antigen 19-9 (CA 19-9), carbohydrate antigen 72-4 (CA 72-4), and squamous cell carcinoma (SCC) is controversial. The gene discussed is CEACAM5; the disease is squamous cell carcinoma.