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.