Cancer Biomarker Concentration Changes During Tumor Progression

Most circulating cancer and other disease biomarker concentrations increase during disease progression, roughly correlating with tumor burden or disease severity. During the biomarker discovery phase, several studies (some published in high-impact journals) report decreases in serum biomarkers at the time of disease diagnosis or during progression (in comparison to control, non-diseased populations). It is suggested these biomarker decreases between normal and diseased populations may have utility in diagnostics. We briefly examine if a serum cancer biomarker concentration is likely to decrease as cancer progresses through empirical data. We propose a simple model, which, if correct, would suggest that in most cases, the biomarker decrease during disease progression could be an artifact or epiphenomenon (thus representing false discovery). Our suggestion is supported by the very few examples of decline of serum biomarkers during cancer development and progression. The notion that a serum biomarker concentration could be inversely associated with tumor burden seems to be an epiphenomenon.