Within-Subject Variation of Carcinoembryonic Antigen in Colorectal Cancer — Application of Reference Change Values and Individual Reference Ranges to Patient Follow-Up

Abstract

Dynamic interpretation of results is an alternative approach to the conventional cut-off procedure. Reference change limit is a valuable reference point to interpret dynamically tumour marker values when only very few serial results can be obtained from a patient after treatment. In this paper, a reference change limit of 2.0 μ §/1 was estimated for carcinoembryonic antigen in patients with complete remission of colorectal cancer. This figure means that a difference greater than 2.0 μg/l has at least a chance of being statistically significant (at 0.05 probability). As complementary information to the reference change limits, with more than four successive results, a simple time series model can be used to obtain predictive limits for the next observation.

Reference Change Value for α-Fetoprotein and Its Application in Early Detection of Hepatocellular Carcinoma in Patients with Hepatic Disease

“…The RCV has been determined for various constituents in healthy persons and in some pathologies (7)(8)(9)(10)(11)(12)(13). In diseases that can modify the homeostatic set point and the degree of fluctuation of a specific constituent, the withinsubject biological variation (BV) may be different from that of persons who do not have these diseases (13)(14)(15).…”