Biomarker screenings include analyses of proteins (proteomic analyses), gene expressions,
and chromosomal abnormalities. In cancer, a combination use of these tools can help
define pathogenic pathways more than using any of these approaches alone. This may
lead to less empiric and more biologically-oriented tumor identification.1
Biomarker screenings have helped improve the accuracy of diagnosis and prognosis
of some cancers, and have provided the basis for identification of more personalized
treatments.1
Proteomic Analyses
Proteomic analyses (e.g., 2D gel electrophoresis, liquid chromatography, mass spectrometry)
can help identify, characterize, and quantify protein biomarkers. While they are
more potent in analyzing a large number of proteins and can be reliable and effective,
they cannot be used in a high-throughput fashion.2
Gene Expression Analyses
Microarray/gene chip technology is a fast method that can identify thousands of
genes at once. It can show how actively specific genes are being turned on in a
specific tumor, and also can detect alterations in chromosomes that occur when cells
become malignant. These tests are very powerful, but the list of genes identified
in this way often varies and may not be always reliable.
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- Quantitative RT-PCR, or quantitative real-time reverse transcriptase polymerase
chain reaction, requires small amounts of tissues and delivers quantitative estimates
of gene expression. However, genetic material (RNA specifically) can be easily degraded.
This technology can therefore be challenging with some preserved tissues.4
Chromosomal Abnormalities Analyses
Chromosomal abnormalities are caused by errors in the number or structure of chromosomes.
These tests are commonly used:
- FISH (Florescence In Situ Hybridization):
According to the National Human Genome Research Institute, FISH provides researchers
with a way to visualize and map the genetic material in an individual’s cells, including
specific genes or portions of genes. This is important for understanding a variety
of chromosomal abnormalities and other genetic mutations. Unlike most other techniques
used to study chromosomes, FISH does not have to be performed on cells that are
actively dividing. This makes it a very versatile procedure.
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- ImmunoHistoChemistry (IHC) Analysis:
IHC uses specific antibodies to visualize cellular protein expression through staining.5 It can accurately detect protein overexpression typical
of some malignant tumors with remarkable sensitivity and specificity. It can be
used with formalin fixed material and other common fixatives.6
A relatively simple technique, IHC outcomes depend on the experience of the clinician
who performs the reactions and interprets the results.5