- Is Cancer a genetic disease?
- How do gene mutations cause cancer?
- Why are breast cells so susceptible to becoming cancerous?
- Why is there such a difference in how patients individually respond to cancer drugs?
- What is a pathology report?
- What is gene expression profiling?
- How will a gene expression profile test benefit me?
Is Cancer a genetic disease?
When talking about a genetic disease we are normally speaking about a single gene disorder. There are thousands of single-gene diseases including achondroplasia, cystic fibrosis, hemophilia, Huntington disease, muscular dystrophy and sickle cell anemia to name only a few. Single-gene diseases usually follow simple Mendelian patterns of inheritance - autosomal dominant, autosomal recessive, or X linked.
Cancer is not a single gene disease but rather a polygenic disease involving hundreds of genes that may differ among patients even though they have been diagnosed with the same condition. Some gene mutations may be inherited like BRCA1 and BRCA2 but most are somatic; mutations acquired during a person's lifetime and are not inherited. Other conditions that do not alter a genes sequence but alter its activity are also involved. This gene altering behavior is called "epigenetic." Gene mutations like BRCA1 or BRCA2 increase a woman’s odds of developing cancer but many more genes must mutate before this will occur.
How do gene mutations cause cancer?
Genes are responsible for all the activities that go on inside any of your cells. They produce the proteins that carry out all of life’s functions. The cells ability to regulate its reproductive rate is of major importance. Remember you start from one cell, a fertilized egg, and eventually turn into trillions in a very controlled manner. A cell that is dividing uncontrollably and can invade and damage normal tissues is cancer. The dividing of a cell from one into two is an incredibly complex process involving thousands of genes and the proteins they produce. If a number of genes in a cell are altered, either by mutation or epigenetic factors, the cell becomes a renegade and begins dividing without considering the community to which it belongs.
Why are breast cells so susceptible to becoming cancerous?
The tendency for any cell to develop into cancer involves its basic nature, whether it is the type of cell that divides frequently or not (breast cells versus brain cells for instance). Cells that multiply rapidly are closer to behaving like cancer cells than those that multiply slowly. Also, cells that are exposed to cancer-causing agents are more likely to incur genetic changes and become malignant. Finally, cells that have trouble detecting and repairing damaged DNA are also more likely to become cancerous. The types of cells that fit all three categories have a greater tendency to accumulate all the small mutations and epigenetic factors that are necessary to promote the growth and spread of cancer. In most cases breast cancer takes years to develop and become detectable with today’s imaging technology. During the years between puberty and a woman’s first full-term pregnancy, all three of the above categories are met by maturing breast cells.
Why is there such a difference in how patients individually respond to cancer drugs?
A large percentage of patients are poor or non-responders to almost all commonly prescribed drugs, including drugs used in breast cancer therapy. This is due to genetic variations found in all individuals. We are 99.9% the same but that .1% difference is responsible for your uniqueness; it also determines how you react to and metabolize any particular drug. Identifying and measuring the genetic variations involved is crucial in predicting whether a patient will have a good response to a drug, a bad response, or no response at all.
What is a pathology report?
Presently the most important contributors to assessing your breast cancer are determined by experience and the use of a microscope. Pathologists are disease specialists who visually study cells and tissues to determine whether they are cancerous, precancerous or harmless. They determine the stage of a tumor by measuring its size and how far it has spread. They grade it by determining the extent to which the cells have taken on an abnormal appearance and how aggressive it appears based on their experience. This report, along with other pertinent clinical data, assists the physicians on your team to plan your course of treatment. Most physicians have not been trained in the relatively new field of genomic medicine. Genomic medicine enables physicians to go beyond the visual (the effect) and "see" the molecular activity causing the cells cancerous behavior. Unfortunantly, most pathology reports do not include genomic testing which would dramatically increase the information physicians need to evaluate the best possible therapy for each individual patient.
What is gene expression profiling?
We all start life as a single cell with chromosomes and their accompanying genes. Our original cell grows and divides, eventually leading to many cell types with specific functions. With only a few exceptions, every cell of the body contains a full set of chromosomes with their accompanying identical genes, but only a small fraction of these genes are active in any particular type of cell. A brain cell and a breast cell have very different jobs to perform in the body. "Gene expression" is the term used to describe the transcribing of the information contained within the DNA, the repository of genetic information, into messenger molecules. These molecules are then translated into the proteins that perform most of the critical functions of cells. The "expression" of these specific genes is what creates a cell’s unique capabilities. If you were to record someone debating, you’d be very aware of the volume variation in her speech. Gene expression profiling would be like that recording. You are measuring the "volume" of the genes activities. Are they talking too loudly, too softly, just right or something in-between? The proper and harmonious expression of a large number of genes is a critical component of normal growth and development and the maintenance of proper health. Disruptions or changes in gene expression are responsible for diseases like breast cancer.
How will a gene expression profile test benefit me?
A gene expression profile test will give you the most accurate diagnosis and predict, with a high level of certainty, the prognosis of your disease. Breast cancer is clearly a genomic disease involving many genes. The ability to measure how specific genes are reacting in cells that are multiplying out of control is crucial in understanding and treating the disease. Physicians’ work with the tools that are available to them and, until now, a microscope and genetic tests that only look at one or a few genes were all they had. The ability to look at the expression patterns of all the genes scientists have determined are involved in breast cancer gives physicians the necessary molecular view of the disease. Until Iris BioTechnology's technological breakthrough in clinical expression profiling, there were no comprehensive tests available for all women with breast cancer.