Preliminary investigation of a new serum marker for ovarian cancer

Abstract Objectives: The long-term survival rate of patients with carcinoma of the ovary is poor, because this condition is usually diagnosed at an advanced stage of the disease. A reliable diagnostic and screening test is still lacking. Therefore, a serological test for a novel ovarian tumour antigen was developed and investigated in a clinical setting. This report describes this investigation, the aim of which was to provide data to decide whether the test warrants a further, large-scale trial. Methods: Serum collected from 25 patients with ovarian carcinoma, 24 healthy controls and 25 control patients with non-carcinomatous ovarian disorders was tested. The test utilises a monoclonal antibody, designated SMO47, to capture the tumour antigen and a normal form of the antigen from serum. Only the tumour antigen is detected by biotinylated Maakia amurensis lectin, which binds specifically to the sialic acid on the tumour antigen. Results: The sensitivity for the carcinoma patient group was 60% and the specificity for the control patient group was 76% when a cut-off value for 100% specificity in the healthy controls was used. The area under the receiver-operator characteristic curve was 0. 8200. CA125 tests were done on all serum, and the results compared graphically. The tumour antigen in the serum was very stable and did not seem to be affected by freezing or long storage at 4°C. Conclusions: The results of this first application of the new test are encouraging and warrant further investigation and testing of larger numbers of subjects to obtain more significant values for the sensitivity and specificity.