tumor markers Flashcards
second leading cause of death in north america
cancer
definition of cancer
uncontrolled growth of cells that can develop into a tumor and spread to other areas.
cancer is staged based on
tumor size, histology, regional lymph node involvement, presence of metastasis (1-4)
stage 1 cancer
localized tumor
stage 2 cancer
invasion of primary tumor thorugh epithelium and into blood vessels
stage 3 cancer
migration of tumor into regional lymph nodes
stage 4 cancer
metastasis of tumor to distant tissues (ex. lung, heart)
tumor origin in epithelial tissue
carcinoma
epithelial cells that form glandular structures
adenocarcinoma
supportive or connective tissue tumor (ex. muscle, bone, catilage, fat, blood vessels)
sarcoma
cancer in lymphoid tissue
lymphoma
cancer of melanocytes
melanoma
cancer of white blood cells
leukemia
enzyme tumor marker
levels of enzymes correlate with tumor burden.
ex. ALP: bone, liver, intestine
serum proteins (B2-microglobulin and immunoglobulins) as tumor markers
multiple myeloma light chains
hormones and metabolizes as tumor markers
specific markers of secreting tumors (ex. ACTH: Pituitary adenoma and ectopic lung tumor)
oncofetal antigens as tumor markers
present during fetal devleopment but found in adults. (ex. carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP) )
CEA is associated with what cancer
colon cancer
presence of estrogen receptor assay and progesterone receptor assay suggests what
that tumor will respond to treatment
why would screening asymptomatic populations result in detection of false positives
most tumor markers are found in normal cells, not just cancer cells (ex. PSA)
diagnosis of cancer
uses results from markers, imaging, risk factors, and symptoms
prognosis of cancer
concentration of the marker determines prognosis (highest levels associated with metastasis)
decreased levels of tumor markers indicate therapy is working, increased levels of tumor marker may indicate what
need for change in therapy
detection of recurrence
once tumor is removed, elevations of marker can indicate regrowth
ideal tumor marker
tumor specific
absent in healthy individuals
readily detectable in bodily fluids
diagnostic sensitivity
likihood that given the presence of disease, an abnormal test result predicts the disease
diagnostic specificity
likelihood that given the absence of disease, a normal test result excludes the disease
why is it not best practice to compare test results from two different assays for a cancer diagnosis
differences in antibody specificity, lack of standard reference material, variation in reference ranges
most common tumor marker measurement
immunoassay
challenges of immunoassay
levels above linearity, may show hook effect, samples exceeding range should be diluted.
tumor marker interferences
heterophile antibodies
lipemia
hemolysis
other tests used for tumor markers
high-performance liquid chromatography
immunochemistry (test solid tissue…ERA, PRA)
what is AFP
an abundant protein synthesized by fetal liver
when would AFP be increased
patients with hepatoellular carcinoma, and testicular cancer.
decreased in down syndrome, increased in spina bifida
function of AFP
normally functions as transport protein, and is involved in regulating oncotic pressure
cancer antigen 125
detecting and monitoring ovarian tumors
annual test
carinoembryonic antigen (CEA)
expressed during development.
CEA (nonspecific marker) indicates what
colorectal cancer, also incresed in lung, breast, GI tumors, pancreas, thyroid, and ovarian cancer.
not diagnostic
human chronic gonadotropin (hCG)
secreted by placental to maintain pregnancy
hCG as a tumor marker
testicular cancer, gestational trophoblastic diseases
hydatiform mole, choriocarcinoma
prostate specific antigen
glycoprotein produced in prostatic ducts. regulates seminal fluid viscosity
patients with prostate levels have ____ level of free PSA
decreased
normal range for PSA
<4ng/mL
CA 15-3
metastatic cancer of breast
