23) Tumor markers Flashcards
(114 cards)
Molecule may be a product of the malignant tissue, or it may be a substance produced by the body in response to the malignancy
tumor marker
Because most tumor markers are molecular forms that exist at some level in normal, benign, and malignant neoplasia, they are not…
specific enough to be used as a means of screening an asymptomatic population
t/f tumor markers are diagnostic for cancer
false; rarely
PSA is an exception
first tumor marker
BJ protein for MM
Alpha-fetoprotein (AFP) used to screen for hepatoma in…
a Chinese population that had a high prevalence of that disease
Prostate-specific antigen (PSA) used to screen…
men over 50 years
elevated tumor marker may confirm dx if pt has…
Signs and symptoms of the disease and risk factors for the disease
Serum levels of tumor markers are widely accepted as useful for…
monitoring treatment of diagnosed disease states
3 considerations to make when evaluating utility of tumor markers
- A single result should not be used to make or confirm a diagnosis.
- Values obtained from different manufacturers’ test kits cannot be used interchangeably.
- Physiology of the body must be taken into account when evaluating the significance of a tumor marker result.
criteria for an ideal tumor marker
- Easy and inexpensive to measure
- Specific to the tumor
- Direct relationship between blood levels of the marker and tumor mass
- Abnormal plasma level, urine level, or both
- Levels that are stable and not subject to aberrant fluctuations.
- If the tumor marker is present in plasma of healthy individuals, it should exist at a much lower concentration than that found in association with all stages of cancer.
Measure of how often the assay system detects the biomarker when the disease is present
sensitivity
Used to describe the probability that a laboratory test will be negative in the absence of disease
specificity
the probability that a disease is present when the test is positive or that a disease is absent when a test is negative.
predictive value
positive predictive value =
100(TP)/(TP + FP)
negative predictive value =
100(TN)/(TN + FN)
sensitivity =
100(TP)/(TP + FN)
specificity =
100(TN)/(TN + FP)
A measure of how often the assay system detects the biomarker when the disease is present
diagnostic sensitivity
The probability that a lab test will be negative in the absence of disease
diagnostic specificity
combining multiple modes of genomic analysis: gene- and exon-level expression, DNA variation, and copy number data to fundamentally improve our understanding of the disease
microarrays for cancer detection
Prior to 1950s, —— were the only tumor markers available
enzymes
alk phos sources
Liver, bone, intestine, and placenta
normal increased levels of alk phos
pregnant women
growing children
help differentiate source of elevated ALP
5’-nucleotidase
γ-glutamyl transferase (GGT)
ALP isoenzymes