401 Ca125 Use in Clinical Practice

Introduction: The CA125 antigen is a high molecular weight glycoprotein, which is expressed by a significant proportion of epithelial ovarian cancers. The sensitivity and specificity of CA125 is known to be poor and at present there are no guidelines produced by the Royal College of Pathologists or the Association of Clinical Biochemists to aid clinicians or laboratories on its most appropriate use. Aim: to identify the patient population having a CA125 measurement and to determine its contribution to individual patient management. Methods: A retrospective case note audit. Results: 799 patients were included in the audit, 94% female and 6% male; of these patients 26% of females and 46% of males had an abnormal result. CA125 was mainly used to investigate a wide range of signs and symptoms and only 6% of tests were for follow-up and 3% for screening of ovarian cancer. Ovarian cancer was the final diagnosis in 21% of females with a raised CA125. False positive results were largely due to another malignancy (29%), benign ovarian pathology (11%), benign gynaecological conditions (8%) and hepato-biliary disease (6%). The specificity of CA125 for ovarian cancer increased with levels over 1000 kU/L. Conclusions: The results of this audit confirm the high false positive rate and lack of sensitivity associated with CA125. There is substantial inappropriate usage of CA125 which has led to results which are of no use to the clinician, have cost implications and add to patient anxiety and clinical uncertainty.