HLA-G and cancer: 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.