Tumor Markers Flashcards
What produces tumor markers?
The tumor itself or as an effect of tumor on healthy host tissue
What are tumor markers used for?
Screening Diagnosis Prognosis Monitor therapy Detect recurrence
T/F: Most tumor markers are also present in normal, healthy tissue or benign conditions
True
T/F Specific quantity of a TM is more important than the rate of increase in determining a patient’s prognosis
False. Rate of increase (velocity) is more important.
Highest levels of TM seen when tumor _______
metastasizes
3 things that make a good tumor marker
- Specific
- Absent in normal population
- Readily detectable
4 categories of commonly used tumor markers
- Enzymes
- Proteins
- Hormones/hormone metabolites
- Oncofetal antigens
Why is measuring B-2 microglobulin useful?
It’s found on the surface of nucleated cells. Measures cell turnover.
Used to monitor renal transplant patients for rejection.
How do we detect tumor makers?
Quantitative immunoassay
What is the hook effect?
What happens when analyte exceeds analytical range. Labeled antibodies are saturated and a “sandwich” is not formed. This causes a reduction in signal as the concentration increases. The line plotted is curved, not linear.
How do we compensate for the hook effect?
Dilute the sample
What may interfere with TM detection/measurement?
Icterus, lipemia, hemolysis
Cross-reacting antibodies
Carry-over (from reusable probe, etc.)
What is alpha-fetoprotein measurement used for?
Diagnosis and prognosis of hepatocellular carcinoma
Also seen in germ cell tumors
AFP with beta-HCG can be used to classify & stage _______ cancer
testicular
Is AFP completely specific?
No- increases seen in pregnancy, liver disease
What level of AFP is diagnostic of HHC in high-risk patients?
> 500 ng/mL (The higher, the worse)
AFP is usually synthesized by the _____ _______
fetal liver
What is CEA (carcinoembryonic antigen) used to detect?
Relapse of colorectal cancer (after diagnosis has been made)
Is CEA useful as a screening test for colorectal cancer?
No- it is not tumor-specific; may be elevated in other conditions
HCG is normally secreted by cells of _______ to prepare and maintain pregnancy
placenta
How is HCG used as a tumor marker?
Prognostic indicator of ovarian cancer
Diagnostic marker to classify testicular disease
Helps detect Gestational trophoblastic disease
Prostate specific antigen (PSA) is only produced by…
epithelial cells of prostatic ducts in prostate
What is PSA best used for?
Monitoring the progression of prostate cancer after therapy
Why would we measure both total and free PSA?
Total PSA (measures free & complexed PSA): screen for & monitor prostate cancer
Free PSA: patients with malignancy may have lower free PSA
T/F Prostate cancer may be present at normal PSA concentration
True
What is CA-125 used to detect?
Ovarian cancer
Is CA-125 used to screen asymptomatic patients?
No. Although it may be used to screen high-risk patients (family Hx or prior Hx of ovarian cancer)
T/F CA-125 levels do not correlate with stage of cancer
False- they do correlate
CA-125 is only clinically accepted marker for ______ _______
Ovarian cancer
Can CA-125 be used to distinguish ovarian cancer from benign masses?
yes- benign masses don’t secrete this tumor marker
What is CA 19-9 used for?
To differentiate between pancreatic cancer and other cancers
Monitor treatment & recurrence
High levels of CA 19-9 correlate with…..
disease progression, outcomes
Is CA 19-9 useful as a screening tool?
No
What is CA 15-3 used for?
Monitoring breast cancer treatment and disease recurrence
Can 15-3 be used alone to come to a diagnosis?
No- needs to be combined with history, physical exam, imaging
Why are 19-9 and 15-3 not useful as screening tests?
Levels may be increased in other benign or malignant conditions. May also be up in healthy individuals.
How can an elevated CK level from cancer be differentiated from elevation due to MI?
MI will cause CK to increase and then decrease.
In cancer, CK will increase and remain elevated
What are useful protein markers?
What makes a good marker?
Albumin, transferrin, prealbumin
Short half-life makes a better marker
If transport protein levels are decreased, how can we tell if this is from inflammation or malnutrition?
CRP- high in inflammatory conditions
T/F: Albumin levels can classify severity of malnutrition
True
Definition of Kwashiorkor
Chronic protein deficiency with adequate non-protein intake.
S/S of Kwashiorkor
low albumin, edema, hepatomegaly
Definition of Marasmus
Deficiency of calories with adequate protein intake
S/S of Marasmus
Severe reduction in body weight (thin with wasting muscles), normal albumin levels, edema is rare
Why is transferrin a better marker of protein depletion than albumin?
Shorter half-life
Transferrin in synthesized by the _________. It binds and transports _____ _______.
liver
ferric iron
Increased transferrin levels can indicate iron ________
deficiency.
Can transferrin be used to diagnose malnutrition?
Maybe
What are the main roles of pre-albumin?
Transport thyroxin and Vitamin A
What do levels of Pre-albumin <80 mg/dL indicate?
severe protein-calorie malnutrition
Pre-albumin levels can also be used to monitor _____ in diabetic patients with ulcers or post-op patients
healing
What is another name for pre-albumin?
Transthyretin
