Genetic alterations are key factors in breast carcinogenesis. However, it is not fully understood what causes the genetic damage. Is it the woman’s environment or her life that does the damage? Or is it hormones? If so, is it her own, or the ones she takes? Or is it toxic chemicals or a virus or radiation that causes these alterations? If it were possible to identify the causes and block or eliminate them, it wouldn’t matter quite as much which genes were being altered.
A good example is lung cancer. It is well known that cigarette smoking triggers the disease, so it must cause the genetic alterations. Thus, it is less crucial to find out what the alterations are, because it is not necessary to neutralize the causative genetic alterations. People can just be told to stay away from cigarette smoke and, if they do so, that will tremendously reduce the risk of lung cancer. So in the case of breast cancer, thinks like diet, alcohol consumption, hormone replacement, pesticides in the environment and electromagnetic waves are currently being studied to find carcinogens, but so far, none has been found equivalent to smoke in lung cancer. Both the environmentalists and the basic researchers are right, at least to an extent. You can’t simply say, “Toxic chemicals are the cause of cancer”. Alone, they are not. Many people are exposed to environmental toxicants such as pesticides and never develop cancer. But on the other hand, you can’t also simply say, “All cancers are genetic, environmental contaminants are irrelevant”. It is the interaction between genes and the environment that will, in the end, explain cancer.
Another important aspect of breast cancer genetics are very important genes called tumor suppressor genes. These genes tamper with oncogenes (genes that have mutated) and proto-oncogenes (normal, non-mutated genes). These genes serve as breaks for the cell cycle system. While there are some genes that push the cells to grow and divide, tumor suppressor genes function in reverse to this. Sometimes, this happens because the cell is defective; in which case the tumor suppressor gene signals the cell to stop replicating or, in some instances, causes the cell to undergo a programmed type of death, known as apoptosis.
The tumor suppressor gene, p53, keeps cells with DNA mutation from dividing. It is believed that BRCA 1 and BRCA 2, which are breast cancer genes, are actually tumor suppressor genes normally functioning as DNA repair molecules. Since these genes maintain the balance in the cell cycle system, mutations or loss of function could be disastrous for the cell.
In most cancers, there is not just one but several mutations. One of the more important questions is whether the mutations come in sequentially. Will one develop breast cancer is she has the oncogene Her-2/neu mutation initially, followed by alteration of the tumor suppressor gene p53, but not if the p53 mutates first? There is still so much to be discovered with regard to the genetic causes of breast cancer. We don’t have the answers yet, but we are definitely on the verge of solving the mystery.