| Proto-oncogenes are normal genes involved in | | | | oncogene. The cancer cells are still contained |
| making cells differentiate and divide. When these | | | | within the breast duct, but they have been |
| genes are mutated, they are then called | | | | programmed to grow much faster because of |
| oncogenes. Proto-oncogenes involved in breast | | | | the over expression of such oncogene. Although |
| cancer are mostly those that cause more cell | | | | Her-2/neu oncogene was first identified in breast |
| division by making the cell cycle go faster and | | | | cancer, research is also being done to see if it is |
| accelerate. They are involved in pushing cell | | | | also involved in other cancer types such as lung, |
| division harder, stronger and faster. | | | | pancreas and ovary cancer. |
| One of the proto-oncogenes is related to the | | | | For breast cancer to have an invasive nature, it |
| epidermal growth factor receptor. This receptor | | | | needs more than one genetic alteration. So long |
| plays a vital role at certain times of the life cycle, | | | | as there's only over expression of Her-2/neu |
| such as puberty, when big changes are going on | | | | oncogene, the cancer will remain confined within |
| with body growth, wherein a protein known as | | | | the breast duct. If it requires other forms of |
| epidermal growth factor functions to promote cell | | | | genetic alterations, one that causes cancer cells to |
| growth. This protein binds to an epidermal growth | | | | move out of the ductal region or make new |
| factor receptor and signals the cell to grow. When | | | | blood vessels (angiogenesis), then it can spread. If |
| the proto-oncogene for the receptor is over | | | | the cancer patient has these invasive cancer |
| expressed, it doesn't wait for the epidermal | | | | alterations and one of the accelerated cancer |
| growth factor receptor to tell it to grow. Instead, | | | | growths, then it is worse. People with both of |
| cells begin to grow independently, just like getting | | | | these genetic alterations have a worse prognosis |
| stuck in the "ON" position. | | | | than with only one type of alteration alone. |
| Another type of epidermal growth factor | | | | Cancer not only requires excessive cancer cell |
| receptor is a subtype, the epidermal growth | | | | proliferation, it also has to invade, grow new blood |
| factor receptor 2. This receptor is more | | | | vessels and spread from the breast area. |
| commonly known as Her-2/neu oncogene. The | | | | One of the fascinating things that have happened |
| type of genetic alteration that Her-2/neu has in | | | | in recent years is that there is now an antibody |
| breast cancer is known as amplification. Instead of | | | | to counteract the Her-2/neu receptor, which can |
| having only one copy during cell division, the cell | | | | be given intravenously to breast cancer patients. |
| makes numerous copies of this gene, about ten | | | | It has quite a unique mechanism of action. It |
| to sixty times more. Either the gene over | | | | attaches only to cells with too much Her-2/neu |
| expression or the extra protein can be measured | | | | receptor, not the normal ones, so that while it |
| in a woman's cancer by examining the cancer | | | | antagonizes Her-2/neu cells, it leaves the other |
| tissue that has been resected. Since Her-2/neu | | | | cells unaffected. Unlike chemotherapy, with which |
| oncogene encodes a growth factor receptor, it | | | | case most dividing cells are destroyed, it is a |
| functions in signaling the cells to grow faster and | | | | targeted therapy. So far, this treatment has been |
| faster, although it is not involved in cancer | | | | used only in metastatic breast cancer, but it has |
| invasiveness. About 70 to 80 percent breast | | | | implications for disease that hasn't spread yet. |
| precancers have over expression of Her-2/neu | | | | |