Cancer Markers Flashcards
cancer definition
uncontrolled growth of cells to form either a tumor or spreading to many other body areas (metastasis)
cancer genetics
tumors from inherited or aquired genetic mutations that activate growth factors & oncogenes while inhibiting apoptosis, tumor suppression genes & genes that regulate cell cycles
what is seen with a metastasis cancer
less cell adhesion & more genetic changes
ideal tumor markers would:
be tumor specific
absent in healthy people
readily detectable
useful in both screening & diagnosis
screening tumor markers:
when there is one marker that aids in IDing w/ some certainty that you have the disease
prognosis tumor marker
more marker present the more cancer present
going into metastasis
monitoring tumor marker
use tumor marker as tool for monitoring patient after drugs, radiation, or chemotherapy
QC issues for tumor marker assays
antibodies used are variable analytes are heterogenic lack reference material; lack calibrators kinetics unknown lack standardized reference ranges
how to make tumor marker assays the most accurate as possible
test patient w/ same tumor marker from same kit & same methodology
use same reagent lot
common carcinomas
lung breast colon bladder prostate
common sarcomas
fat
bone
muscle
alpha-fetoprotein and liver cancer
used to monitor hepatocellular carcinoma (HCC)
used for diagnosis, staging, prognosis & monitoring treatment of HCC
>1,000 ng/ml is a poor prognosis for HCC
alpha-fetoprotein & testicular cancer
used to classify stage of disease & for monitoring treatment of testicular cancer
10-20% increase = stage I
50-80% increase = stage II
90-100% increase = stage III
AFP assay type
immunassays w/ ‘sandwich’ type assays
CA-125
cancer antigen 125
used to detect & monitor ovarian tumors
not used for mass screenings
contains putative transmembrane region & a tyrosine phosphorylation site
not normally seen in serum
stages of ovarian cancer & CA-125
50% increase = stage I
90% increase = stage II
>90% increase = stage III & IV
carcinoembryonic antigen (CEA)
oncofetal antigen- immunoglobulin that is part of group involved in apoptosis, immunity & cell adhesion
often expressed on tumor
not used for screening; used for monitoring & checking for re-occurrences
cancers that often express CEA
colorectal
lung
breast
GI
specificity of CEA
non-specific
associated w/ loss of cell adhesion (malignancy)
human chorionic gonadotropin (hCG)
secreted from trophoblasts of placenta to maintain the corpus luteum during early pregnancy
also elevates in trophoblast tumors, choriocarcinoma & germ cell tumors of ovary & testes
assay for hCG
hCG as a glycoprotein, has a alpha & beta subunit
look for free beta subunit as well as intact hCG forms
hCG can indicate?
ovarian cancer
diagnostic for testicular cancer
most useful for detection of gestational trophoblastic diseases
aggresstive lung cancer
4 distinct tumors of gestational trophoblastic disease
hydatidform mole
gestational trophoblastic neoplasms
choriocarcinoma
placental site trophoblastic tumors
cancer hormone markers
PTH calcitonin ACTH Serotonin Growth hormone ADH
hormone receptors & cancer treatmenet
if hormone receptors are present - use hormone therapy
if not present - use chemotherapy
prostate specific antigen (PSA)
mild protease activity
glycoprotein from ch 19
has chromotrypsin-like & trypsin-like activity
a serine protease for kallikrein family
normal - should mostly be in the prostate
cancer- significant amount of PSA leaks into blood vessel
2 forms of PSA
free PSA
PSA complexed with alpha-1-antichymotrypsin (ACT) or alpha-2-macroglobulin (A2M)
most assays recognize 90% ACT & 10% free PSA or 100% free PSA
other causes of increased PSA
prostate infection
irritations
benign prostate hyperplasia
digital rectal exam prior to blood draw for PSA
enzyme cancer markers
alkaline phosphatase
lactic dehydrogenase isoenzymes
prostate specific antigen
neuron-specific enolase
suppressor p53
tumor suppressor protein that triggers cell apoptosis
BRCA1 & BRCA2
present in some breast cancer patients
bcl-2
may be involved in apoptosis in breast cancer
suppressor genes includ
p53
retinoblasoma gene
p21
