Diagnostic significance of carcinoembryonic antigen levels in serous effusions. Correlation with cytology.

Carcinoembryonic antigen (CEA) determinations were performed in 86 malignant and 103 benign serous fluids submitted for routine cytologic examination. Cytology alone identified 54 (63%) of the malignant fluids. The remaining 32 (37%) had elevated CEA levels but no detectable malignant cells. In nearly half of 67 effusions with CEA greater than 2.5 ng/ml and negative cytology, elevated CEA concentrations were confirmed to be associated with malignancy. Most (92.5%) cytologically positive serous fluids also had elevated levels of CEA. Elevated CEA assay may raise the suspicion of malignancy in serous fluids that are negative cytologically. Increased CEA concentrations alone, however, cannot be used for confirming malignancy because CEA levels greater than 2.5 ng/ ml (mean, 10.5 +/- 8.2) were found in 50% of the fluids proven to be nonmalignant. Fluid CEA was more consistently elevated in tumors of gastrointestinal tract (greater than 25 ng/ml), lung (11.2 +/- 8.9) and breast (11.6 +/- 7.7) than in lymphomas or sarcomas (3.6 +/- 1). Paired plasma and fluid CEA levels may be particularly helpful in confirming a clinical diagnosis of malignancy in cases with negative fluid and biopsy findings.