Download New advances in diagnostic procedures

New advances in diagnostic procedures
I. IMMUNOHISTOCHEMISTRY:
Immunohistochemistry or IHC refers to the process of detecting antigens (e.g.,
proteins) in cells of a tissue section by exploiting the principle of antibodies binding
specifically to antigens in biological tissues. IHC takes its name from the roots
"immuno," in reference to antibodies used in the procedure, and "histo," meaning
tissue (compare to immunocytochemistry)
This involves the detection of cell products or surface markers by monoclonal
antibodies. The binding of antibodies can be detected by fluorescent labels or
chemical reactions that result in the generation of a colored product.
This technique is useful in:
1. Categorization of undifferentiated malignant tumors e.g., cytokeratin in
carcinoma and desmin in tumors of muscle.
2. Classification and categorization of leukaemias and lymphomas; B and T cell
lymphomas can be identified.
3. Determination of the site of origin of metastasis using antibodies against tissue
specific antigens. e.g., thyroglobulin and PSA (prostatic specific antigen) in
thyroid and prostatic neoplasms respectively.
4. Detection of molecules that have therapeutic or prognostic significance e.g.,
estrogen and progestrone receptors in breast cancer. Products of certain cancer
suppressor genes (e.g., p53) and oncogenes (e.g., c-erb B2) can also be
detected. Over-expression of the latter in breast cancer is associated with poor
prognosis.
Immunohistochemical stain of estrogen receptors in CA breast
II. FLOW CYTOMETRY
Flow cytometry is a technology that is used to analyse the physical and chemical
characteristics of particles in a fluid as it passes through at least one laser, cell
component are fluorescently labelled and then excited by the laser to emit light at
varying wavelength, the main application in tumor are:
1- measure the DNA content of tumor cells. Aneuploidy correlate with poor
prognosis in early stage breast cancer, colorectal, prostatic, urinary bladder and lung
cancers.
2- Identification of cell surface antigens by flow cytometry is widely used in the
classification of leukemias and lymphomas.
III-Cytogenetics:
This study include karyotype analysis and abnormal genetics alteration in specific
tumors example of this application are:
1-polymerase chain reaction (PCR)
2-FISH (filter in situ hybridization )
FISH (filter in situ hybridization )
This new teq. Used for detection of specific DNA or RNA in tissue sections or cell
preprations by used of labelled complementary nucleic acid sequence or probe .
This applied for detection of viral sequnce in cells infected by HPV,EBV, or HIV
viruses or any genetics abnormality occur in special types of tumors.
Breast cancer cells, HER2/neu amplified vs. HER2/neu nonamplified - High power These images
show fluorescence in situ hybridization (FISH) of DNA probes to interphase chromosomes. DNA
probes specific for the HER2 gene (red) and a control gene (green) were used on sections taken
from the patient's tumor (left panel) and from a different patient's breast cancer (right panel). HER2
gene amplification is evident in the patient sample on the left.
IV. TUMOR MARKERS:
These are tumor derived or associated antigens, enzymes, cytoplasmic proteins and
hormones that can be detected in blood or other body fluids. They are not primary
methods of diagnosis but are useful adjuncts. They are also of value in monitoring
therapy and in early detection of relapse. Two widely used markers are:
1. Carcinoembryonic antigen. This is normally produced by fetal gut,
liver, and pancreas. It may be elaborated by cancers of the colon,
pancreas, stomach, lung and breast. Less consistent elevations may be
seen in some non-neoplastic conditions e.g., alcoholic hepatitis, cirrhosis
and ulcerative colitis. This antigen is of value in detecting tumor burden
in colorectal cancer and in detecting recurrences after surgery.
2. Alpha-fetoprotein, which is normally produced by fetal yolk sac and
liver. Markedly elevated levels are seen in hepatic carcinomas and nonseminomatous testicular germ cell tumors. Less marked elevations may
be seen in hepatitis and cirrhosis. It is useful as an auxiliary diagnostic
aid of liver or testicular tumors, in monitoring therapy and assessing
recurrence.
TUMOR MARKER
HORMONES
Human chorionic gonadotropin
Calcitonin
Catcholamines and metabolites
Ectopic hormones
ONCOFETAL ANTIGENS
Alpha-fetoprotein
Carcinoembryonic antigen
ASSCIATED CANCERS
Trophoblastic and nonseminomatous germ
cell tumors.
Medullary carcinoma of the thyroid.
Pheochromocytoma and related tumors.
Small cell carcinoma and squamous cell
carcinoma of the lung, etc
Hepatocellular carcinoma and
Nonseminomatous germ cell tumors.
Carcinomas of the colon, pancreas, stomach,
lung and breast.
ISOENZYMES
Prostatic acid phosphatase
Neurone specific enolase.
Prostatic cancer.
neuroblastomas, small cell carcinoma-lung.
SPECIFIC PROTEINS
Immunoglobulins
PSA
Multiple myeloma, NHL
Prostatic cancer.
MUCINS AND
GLYCOPROTEINS
CA-125
CA-19-9
CA-15-3
Ovarian cancer
Colonic and pancreatic cancer
Breast cancer
End