Cancer antigen 125 (CA125) and the law of unintended consequences.

e18327Background: CA125 is a serum tumour marker used to monitor patients with ovarian cancer (OvCa). Its usefulness as a screening tool remains unproven. There is no restriction in its use at our institution, a university teaching hospital. We sought to establish patterns of testing during one calendar year (2013), focussing on the economic costs of such unrestricted testing. Methods: A lookback of the CA125 reports issued by the Biochemistry Laboratory was undertaken. The CA125 requests were from physicians within the hospital & from the community. Individual requests for CA125 & those part of tumour marker panel were included & correlated with radiology & histopathology records to identify subsequent investigations (invxs) & diagnoses (dxs). Economic costings were provided by hospital finance department. For the purpose of this study we only included the costs of invxs triggered by out of range CA 125 test results. Results: In 2013, 7,132 CA125 measurements were performed. 871 repeat tests, 40 tests pe...