The document outlines various cancer biomarkers, including their definitions, classifications (prognostic, predictive), and clinical applications in diagnosis, prognosis, and treatment monitoring. It highlights specific biomarkers such as alpha-fetoprotein, CA-125, and prostate-specific antigen, detailing their relevance to different malignancies and implications in treatment decisions. Additionally, it emphasizes the importance of considering multiple factors when interpreting biomarker test results due to the lack of specificity and sensitivity of individual markers.