Measuring the CSF for certain biological markers of cancer - such as lactate dehydrogenase, β glucuronidase, β2 microglobulin and carcinoembryonic antigen (CEA) – offers another means of making a diagnosis and following the response to therapy.[1] Other useful tests to establish diagnosis and guide treatment include magnetic resonance imaging of the brain and spine and radioisotope CSF flow studies. This evidence concerns the gene CEACAM5 and cancer.