ackgound : Detection of tumor markers could offer an accessible method for screening
risk groups in order to achieve an early diagnosis of cancers, to contribute to an adequate
staging, and to help evaluate effects of therapy. CA 125 is an antigenic determinant defined
by murine monoclonal antibody OC 125, and synthesized by coelomic epithelial derivatives
such as Mullerian epithelum and mesothelial tissues. CA 125 is regarded as useful tumor
marker for non-mucinous epithelial ovarian tumors.
So we investigated whether CA 125 is a reliable tumor marker for gastrointestinal
malignancies and especially for detection of intraperitoneal carcinomatosis unrecognized by
conventional imaging studies.
And we compared CA 125 with other conventional tumor markers in the serodiagnosis of
gastrointestinal malignancies.
Methods ; Serum Ca 72-4, CA 19-9, CA 125 and CEA were determined
radioimmunologically with monoclonal antibodies. A cut-off value of 4 U/ml, 37 U/ml, 35
U/ml and 5 ng/ml were used respectively.
Results ; The results are summarized as follows.
1) CA 125 had high specificity (93%) for benign gastrointestinal diseases but was not
useful to differentiate malignant ascites and benign ascites.
2) In gastric carcinoma, the sensitivity of CA 125 (36%) was not so different of that of
CA 72-4 (36%).
3) In pancreatobiliary carcinoma, the sesitivity of CA 125(55%) was inferior than that of
CA 19-9 (85%), but combined use of these two tumor markers increases sensitivity (95%) for
the diagnosis.
4) The senitivities of CA 125 for 23 early gastric cancer was 9%.
5) The sensitivities of CA 125 for the intraperitoneal carcinomatosis that was not
recognized by conventional imaging studies was 36%.
Conclustion : Our data indicates that CA 125 is not better in the serodiagnosis of
gastrointestinal malignancies than other conventional tumor markers, and CA 125 has a little
predictive value in the diagnosis of intrperitoneal carcinmatosis unrecognized by the
conventional imaging studies. Serum CA 125 elevation in benig or malignant diseases closely
correlated with the presence of ascites.
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