Tumor markers may be defined as which of the following?

Tumor markers may be defined as which of the following?

• A. Biologic substances synthesized and released by cancer cells or substances produced by the host in response to cancer cells
• B. Analytic tests (e.g., immunoassays) used to mark cancer cells
• C. Radioactive substances and chemicals used to help the physician identify cancer cells
• D. None of these

Answer: (A)

Tumor markers are substances that can be measured in body fluids or tissues and come from the tumor itself or from the body's response to the tumor. This matches the idea that a tumor marker is a biologic substance synthesized and released by cancer cells or produced by the host in response to cancer cells. The other ideas describe how we measure or visualize cancer rather than what the marker is: analytic tests are the methods used to detect markers, not the markers themselves, and radioactive imaging agents are tools for visualization, not the markers. In practice, markers like PSA, CA-125, CEA, AFP, or hCG are used to help with screening, diagnosis, prognosis, and monitoring therapy, but their usefulness depends on the cancer type and their specificity.

Tumor markers are substances that can be measured in body fluids or tissues and come from the tumor itself or from the body's response to the tumor. This matches the idea that a tumor marker is a biologic substance synthesized and released by cancer cells or produced by the host in response to cancer cells. The other ideas describe how we measure or visualize cancer rather than what the marker is: analytic tests are the methods used to detect markers, not the markers themselves, and radioactive imaging agents are tools for visualization, not the markers. In practice, markers like PSA, CA-125, CEA, AFP, or hCG are used to help with screening, diagnosis, prognosis, and monitoring therapy, but their usefulness depends on the cancer type and their specificity.