The Roche CEA electrochemiluminescent immunoassay is used. Results obtained with different test methods or kits cannot be used interchangeably. Measurement of CEA has been shown to be clinically relevant in the management of patients with colorectal, breast, lung, prostatic, pancreatic, and ovarian carcinomas. Smokers may have slightly elevated levels of CEA. The CEA assay value, regardless of level, should not be interpreted as evidence for the presence or absence of malignant disease and is not recommended for use as a screening procedure to detect the presence of cancer in the general population.