Learning Objective #1: Identify, articulate, and document assay types for monitoring tumor growth in ovarian cancer patients

Learning Objective #2: Understand the need for consistent assay use for monitoring ovarian tumors in patients and to integrate this knowledge into patient education and teaching

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Articles reviewing CA125 report sensitivity and specificity, which are subject to bias based on assay manufacturer and/or type, source of specimen, and specimen demographics (age, stage, grade, and histopathological tumor type). There are over 38 commercial assays reported in published literature that measure CA125 and these assays fall into 5 major categories: ELISA, IRMA, CLEIA, MEIA, and LIA, in two generations. Despite over 2000 articles published articles since 1981, no comprehensive meta-analysis has been conducted to evaluate the performance of the various assays across patient populations and assay types.

Methods A meta-analytic review was conducted to answer the following questions: 1.) What is the effect of assay type on CA125 measurement? What is the size (magnitude and direction) of the relationship? How linearly correlated are the different assay types? 2.) How precise are first-generation assays as compared to second-generation assays? Eleven studies were included in the analysis and effect sizes with confidence intervals were calculated. Sub-analyses were conducted to understand any confounding of assay performance with serial versus single measurement of patients and between/across assay performance bias based on assay manufacturer, assay generation, and assay type.

Results The second-generation assays performed most accurately and consistently across patient populations and had greater correlation with the control assays than any other type. Assay manufacturer confounded the data and separate analyses show extreme differences in effect sizes

Conclusions Clinical implications include the use of second-generation assays over all others and the same type of assay should be used when serially monitoring patients given the differences in CA125 measurement across assays. Patients should be instructed to have labs drawn at the same lab, or preferably using the same assay during treatment and follow up.