Tumor Markers Flashcards
Define Tumor Marker
Biomarker found in the blood or tissue and when elevated is linked to cancer
How are tumor markers produced?
Directly by the tumor or as an effect of the tumor on healthy tissue
Tumor markers can take the form of what molecule(s)?
Hormones, metabolites, receptors, enzymes, oncofetal antigens
Enzyme tumor markers
Clinically useful for monitoring the success of therapy and correlate to tumor burden
Elevated non specifically
Serum Protein tumor markers
Used to monitor cancer therapy
Beta-Macroglobulin
Is a serum protein tumor marker that is found on the surface of all nucleated cells
A non specific marker of high cell turnover that is common in tumors
Immunoglobulins
A serum protein tumor marker that provides a relatively specific measure of plasma cell production of monoclonal proteins in multiple myeloma
Endocrine Tumor Markers
Used in endocrine malignancies. It is valuable in diagnosing neuroblastomas, pituitary and adrenal adenomas
Oncofetal antigens
Expressed transiently during normal development
Turned on again in formation of tumors
CEA and AFP
Carbohydrate and cancer antigen tumor markers
Monoclonal defined antigens identified from human tumor extracts and cell lines
Best used for monitoring treatment of tumors that secrete these epitopes
Carbohydrate and cancer antigen tumor markers are antibodies that are directed towards what?
Specific carb or cancer antigens.
Best for monitoring treatment of tumors that secrete CA19-9, CA 15-3, CA27-29, and CA-125
Receptor tumor markers are non serological markers that help choose between __a__ and __b__ therapies
A) Endocrine
B) Cytotoxic
What characteristics make an ideal tumor marker?
- Tumor specificity
- Absent in healthy individuals
- Readily detectable in body fluids
T/F:
Tumor markers are found in only cancer
FALSE:
Most are found in normal and benign cells as well as cancer
T/F:
Tumor marker concentration increases with tumor progression
TRUE
Highest level of tumor marker is with ___
Metastasis
What are the two major considerations for tumor marker measurement?
1) Lack of standardization makes comparison of serial results difficult
2) The wide range of tumor marker concentrations encountered clinically
Immunoassays
Common method that allows automation and is relatively easy to use.
What are three unique factors of immunoassays
- Assay linearity
- Antigen excess (hook effect)
- Potential for heterophile antibodies
What is the Hook Effect
When analyte concentrations exceed the analytical range excessively and there is potential for antigen excess.
What should you do if you get a linear result in the immunoassay?
Dilute the specimen and analyze it again. Do not give linear results
What are common analyte concerns with tumor maker immunoassays?
- Icterus
- Lipemia
- Hemolysis
- Antibody cross-reactivity
- Carry Over
What is commonly used to detect endocrine metabolites (small molecules)
High performance Liquid Chromatography (HPLC)
Extractions in HPLC are applied to column and separated by what?
Charge, size, and polarity
T/F:
HPLC is useful to detect hormones and metabolites secreted by tumors. It is helpful in diagnosis, therapeutic monitoring, and recurrence.
TRUE
What are the advantages to HPLC?
- Not subject to Hook Effect
- No lot-to-lot variation
- No interference from heterophile antibodies
What are disadvantages to HPLC?
- Labor intensive
- More experience and skill required than automated