Exam 3 Tumor Markers Flashcards
Functions of tumor marker testing
- Detect and monitor cancer or effectiveness of treatment
- Markers are produced by tumor directly or as an effect of tumor on healthy tissue
- Concentration increases with tumor progression, highest levels when tumors metastasize
Types of tumor markers
- Enzymes
- Serum proteins
- Hormones & metabolites
- Oncofetal antigens
- Receptors
Characteristics of enzyme tumor markers
• Levels of certain enzymes correlate with tumor burden
Examples of enzyme tumor markers
- ALP: bone, liver, intestine
- Amylase: pancreas
- LD: liver, lymphomas
- ACP: prostate
Example of serum protein tumor markers
Multiple myeloma light chains found in urine
Examples of hormone tumor markers
- ACTH: pituitary adenoma and ectopic lung tumor
- HCG: testicular tumor
- ADH: lung carcinoma
- Catecholamines: neuroblastoma
Examples of oncofetal tumor makers
- Carcinoembryonic antigen (CEA) – colorectal
* Alpha-fetoprotein (AFP) – hepatocellular or testicular
Examples of receptor tumor markers
• ERA – estrogen receptor assay
• PRA – progesterone receptor assay
- Presence indicates that tumor will likely respond to treatment
Applications of tumor markers
- Screening populations at risk
- Diagnosis
- Prognosis
- Monitoring response to treatment
- Detection of recurrence
Lab considerations for tumor marker testing
• Standardization between test methods or instruments is not as good as for other common assays
• Comparisons from two different assays can be dangerous due to differences in:
o Antibody specificity
o Assay design and diversity
o Lack of standard reference material
o Variation in reference ranges
• Example: variation in PSA results from two different assays
o Testing done on “access” was consistently higher (1.23x) than testing done on “centaur”
Tumor marker methodology
- Immunoassay - most common
- Advantage: ability to automate testing
- May show the hook effect
AFP tumor marker for:
Hepatocellular or testicular cancer
CA-125 tumor marker for:
Ovarian tumors
CEA tumor marker for:
Colorectal cancer
- > 10 suggestive of disease, > 20 assume metastasis
hCG tumor marker for:
Testicular cancer
PSA tumor marker for:
prostate cancer
- can be elevated in infection, irritate, benign prostate enlargement
- pts with prostate cancer have a lower % of free PSA
PSA range
< 4ng/mL
CA 15-3 tumor marker for:
metastatic breast cancer
CA 27-29 tumor marker for:
elevated in recurrent breast cancer
BRCA1 & BRCA2 tumor markers
hereditary breast-ovarian tumor syndrome
Describe stage I cancer
localized primary tumor
Describe stage II cancer
invasion of primary tumor through epithelium and into blood vessels
Describe stage III cancer
migration of tumor into regional lymph nodes
Describe stage IV cancer
metastasis and invasion of tumor to distant tissues
