Molecular Biology Techniques in Cancer Diagnosis
Cancer is a group of diseases characterized by an uncontrolled division of cells known as proliferation that may lead to invasion and destruction of local and surrounding tissues and organs. This invasion step may be followed by the passage of the invasive cancer cells into the circulatory system and their spreading to other organs of the body via a process known as metastasis . Once in the new tissue, these cancer cells establish a new niche where they began a new cancerous process.
Several factors, such as hereditary or acquired mutational inactivation of tumor suppressor genes, contribute to the transformation of normal cells into cancer cells. Therefore, assessing the stage and grade of cancer progression in patients is key to inform on the severity of the prognosis and type of treatment required. This evaluation process of patients is known as a diagnosis.
Clinical Evaluation of Cancer Patients Using Molecular Biology Technologies
Once a cancer patient is clinically admitted to a hospital or a specialized clinic based on a suspicion of cancer, their clinical evaluation began using imaging techniques (e.g., MRI) and then through the obtention and analysis of blood or tissue samples. The samples are analyzed for the presence of DNA alterations (e.g., mutations or gene expression levels) or anomalies in the expression and levels of proteins. These alterations can then be correlated with the stage and grade of cancer .
DNA alterations are assessed using genomic techniques such as sequencing, gene expression analysis, and bioinformatics analysis of genomic data. Genomic Sequencing is a procedure of determining the order of nucleotides in a DNA section comprising a gene (gene sequencing), while gene expression analysis focuses on determining the levels of gene expression. Bioinformatics relies on powerful algorithms that analyze the genomic data obtained from sequencing and gene expression analyses.
For protein analyses, molecular immunology techniques such as immunohistochemistry (IHC), fluorescence-activated cell sorting (FACS), enzyme-linked immunosorbent assay (ELISA), immunocytochemistry, western blotting, are used to detect the expression levels and alterations of proteins. These techniques rely on the use of antibodies that specifically recognize normal or altered proteins (e.g., proteins with mutations).
Immunohistochemistry is used to visualize and analyze the expression and localization of proteins within the tissues, while immunocytochemistry analyses and visualizes their expression and localization within the cells. Fluorescence-activated cell sorting (FACS) measures the physical and characteristics of a population of cells using antibody labeled cells that are sorted using a flow cytometer. Finally, enzyme-linked immunosorbent assay (ELISA) detects the presence of a protein in a liquid sample using antibodies directed against the protein to be measured.
Although imaging techniques can visualize the presence of cancer within the body, samples analysis of tissues (blood and tissues) from these cancer and metastatic masses requires molecular biology techniques that can provide essential information on the type and causes of the cancer of interest at the genomic and protein levels. The data obtained are critical in informing clinicians and patients on the procedures that are required for the treatment of patients.
 Hanahan, D. and Weinberg, R.A., 2000. The hallmarks of cancer. cell, 100(1), pp.57-70.
 Macdonald, F., Ford, C. and Casson, A., 2004. Molecular biology of cancer. Taylor & Francis.