Carcinoembryonic antigen in the CSF of cancer patients--the value of intrathecal synthesis and correlation with IgA-diffusion dynamics.

OBJECTIVE The diagnostic impact of carcinoembryonic antigen (CEA) was evaluated in serum and CSF of cancer and control patients. METHODS 97 analyses of CEA in CSF and serum from 83 cancer patients were compared with 41 cases without malignancy. CEA diffusion dynamics were evaluated with IgA CSF/serum quotients (Q IgA). Intrathecal synthesis of CEA was analysed both by calculating an index Q CEA/Q IgA and within the IgA-diagram. RESULTS In 73 samples without synthesis of IgA or CEA, both quotients correlated well with a mean Q CEA/Q IgA of 1.1 (95% CI 0.97-1.2). The Q CEA/Q IgA was significantly higher in metastasizing adenocarcinomas than in controls or other malignancies. In leptomeningeal disease from adenocarcinoma, Q CEA/Q IgA was significantly higher than in controls, while patients with CNS and/or bone metastases had intermediate values. The sensitivity to detect leptomeningeal disease was 91% and 69% for brain metastases. Q CEA/Q IgA and CEA synthesis assessed with the IgA diagram were equally sensitive. CONCLUSIONS Evaluation of CEA in the IgA diagram is feasible and of clinical value. The consideration of intrathecal CEA synthesis correlates better with the clinical status than absolute CSF-CEA or the correlation with albumin.