Laboratory Diagnosis of Cancer (M) Flashcards
What are the methods for lab dx of CA?
1) Morphologic methods
a. Cytology
b. Tissue biopsy
c. Immunohistochemistry (IHC)
d. Flow cytometry
2) Biochemical assays
a. Tumor markers
3) Molecular dx
a. Polymerase chain reaction (PCR)
b. Fluorescence in-situ hybridization (FISH)
4) Molecular profiling
a. DNA-microarray
What are the methods under cytology?
1) Exfoliative cytology
a. Cervical Pap’s smear
b. Washings / Brushings
2) Fine needle aspiration biopsy (FNAB)
a. Fluids
i. Pleural
ii. Peritoneal
iii. CSF
iv. Urine
What are the methods under tissue biopsy?
1) Incision biopsy
2) Punch biopsy
3) Core biopsy
4) Cone biopsy
5) Excision biopsy
6) Tissue resection
7) Frozen section dx
What is the characteristic IHC?
It is the basic battery to differentiate tumors
What are the tumor markers under IHC?
1) Cytokeratin
2) Vimentin
3) Leukocyte common antigen (LCA)
4) S-100 / NSE
What is flow cytometry?
It is a rapid and dynamic method of correlated multiparameter, single cell analysis
What are flow cytometers?
These are instruments that determine the characteristics of the cells in a complex cell mixture
What is the action of flow cytometry?
It is designed to enhance microscopic analysis of individual cells using fluorescent substrates and probes
Flow cytometry is originally developed for what purpose?
For the purpose of sorting cells or fluorescence-activated cell sorting (FACS)
What is the mechanism (/ principle / method) of flow cytometry?
1) A suspension of cells (or other biological
particles), either directly or indirectly labeled with
1 or more flourescent probes, is led in a stream
past an illumination and light detection system
2) The cells traverse the illumination spot one by one
3) When the jet stream intersects the laser beam,
fluorescent excitation occurs
4) A microscope objective projects the scatter and
fluorescence light that bounces off the cells to a set
of photomultipliers
5) Temporal, spatial and chromatic filters eliminate
background light and separate the signals from
different fluorophores
6) Digital acquisition electronics measure the
intensity of the light pulses
7) Each cell is measured for light scatter signals and
the presence or absence of fluorescence are
subsequently classified
8) A cell sorter adds a sorting mechanism to a flow
cytometer so that the cells can be separated after
they have been measured and classified
How cell sorting works (/ what is the method of how cell sorting works)?
1) Cells are suspended in a stream
2) Laser beams excite cell fluorescence
3) Signals are measured
4) Stream breaks into drops
5) Drops with cells are charged
6) Electrostatic field deflects drops
7) Drops with cells are collected
8) High speed cell sorters identify and select fluorescent particles at a rate of ~25,000 per second or 100,000,000 per hour
What must be the characteristic of selected fluorochrome rgnts?
Those selected must be suitable for excitation by 488 nm light
What are the exs of fluorochrome rgnts?
1) Fluorescein isothiocyanate (FITC)
2) Phycoerythrin (PE)
3) Propidium iodide (PI)
4) 7-amino-actinomycin D (7AAD)
5) Peridin-chlorophyl-A-protein (PerCP)
6) Dimers of thiazole orange (TOTO-1)
What are the most commonly analyzed clinical materials (/ sxs) in flow cytometry?
1) Blood
2) Bone marrow aspirates
3) Lymph node suspensions
What is the most frequently recommended technique used for sx preparation (for flow cytometry)?
Whole blood lysis
What is the recommended for preparing sxs for FC immunophenotyping of leukemias and lymphomas?
Whole blood lysis
How is whole blood lysis (in terms of sx preparation for flow cytometry) done?
1) Incubation of a fixed volume of anticoagulated whole blood (or bone marrow) with one or more directly conjugated monoclonal antibodies followed by red blood cell lysis, washing, fixation in formaldehyde, and flow cytometric analysis
2) Gating is used for identifying cells/ particles of interest in a mixed population, e.g. non-lysed RBCs, platelets, debris
What are the advantages of doing whole blood lysis (in terms of sx preparation for flow cytometry)?
1) Fewer preparation steps
2) Less sx handling
3) Lower likelihood of differential cell loss
What are the uses of flow cytometry?
1) Immunophenotyping for non-malignant disease
2) Characterization of lymphoid and myeloid malignancies
3) Hematopoietic stem cell enumeration
4) Red blood cell characterization
5) Platelet evaluation
6) Cell function testing
7) Cell cycle and apoptosis assessment
8) Human leukocyte antigen (HLA) typing
What are the clinical applications of flow cytometry?
1) Monitoring AIDS pts
2) Immunophenotyping leukemia and lymphomas and monitoring residual disease
3) Determining CD34 counts for hematopoietic reconstitution
4) Monitoring organ transplant pts for rejection
5) Reticulocyte counts
6) Dx of paroxysmal nocturnal hemoglobinuria (PNH)
7) DNA analysis of S-phase fraction of solid tumors
What are the characteristics of tumor markers (as used in biochemical assays)?
1) Nonspecific due to low sensitivity and specificity
2) Very effective in tumor staging, monitoring, and detecting recurrence
What are the FDA approved kits in connection w/ tumor markers (w/c are being used in biochemical assays)?
1) Alpha fetoprotein (AFP)
2) Carcinoembryonic antigen (CEA)
3) ER
4) Cancer antigen (CA) 125
5) Prostate specific antigen (PSA)
What are the 2 major processes involved in growth (for tumor markers)?
1) Proliferation
2) Differentiation
What is the characteristic of proliferation and differentiation?
Normally, these are well-regulated and under rigid control
What is the effect of loss of regulation (or / in proliferation and differentiation)?
Loss of the regulation increases the risk of these normal cells turning into tumor cells
Is there a tumor-specific marker that is developed and well-studied enough to be widely used in clinical practice?
None yet
True or False
Any cell product may be used as a marker as long as it is related to any event during tumor formation
True
The clinical value of any given tumor marker will depend on what?
On the intended clinical use and the specificity and sensitivity of the tumor marker
What are the types of tumor markers (in terms of identification)?
1) Associated w/ cell proliferation
2) Related to cell differentiation
3) Related to metastasis
4) Related to other tumor-associated events
5) Related to malignant transformation
6) Inherited mutations
What are the exs of tumor markers that are associated w/ cell proliferation?
1) Hormones
a. HCG
2) Serum proteins
3) Enzymes
4) Metabolites
What are the characteristics of tumor markers w/c are associated w/ cell proliferation?
1) Their lvls are increased
2) These are more useful in monitoring pts during treatment
Why are the lvls of tumor markers w/c are associated w/ cell proliferation increased?
Due to high proliferation rate of the cells
True or False
Benign diseases may also involve elevated lvls of tumor markers (w/c are associated w/ cell proliferation), hence, they are not suitable for screening of for CA dx
True
What is the ex of tumor markers w/c are related to cell differentiation?
Most are carcinoembryonic proteins
What are the characteristics of tumor markers w/c are related to cell differentiation?
1) Measurement rely on immunoassay because their conc. in the serum is in nannogram/mL lvls
2) Correlates well w/ tumor activity and can be used to predict px
3) Generally, they are not suitable for screening because:
a. Polyclonal Ab directed against these proteins often cross-react w/ normal proteins
b. Do not appear sufficiently early in the blood from CA pts