The initiation of cell transformation is generally associated with genetic alterations in normal cells that lead to the loss of intercellular-and/or extracellular-matrix- (ECM-) mediated cell adhesion. The initiation of cell transformation is generally associated with genetic alterations in normal cells that lead to the loss of intercellular-and/or extracellular-matrix- (ECM-) mediated cell adhesion.
1 Fail to stop uncontrolled cell growth. 2  Normal cells know when to stop growing so that you have just the right number of each type of cell. 3  Cancer cells lose the controls (tumor suppressor genes) that tell them when to stop growing. A gene mutation can instruct a healthy cell to: 1  Allow rapid growth. 2  A gene mutation can tell a cell to grow and divide more rapidly. 3  This creates many new cells that all have that same mutation. 4  Oncogenes. Oncogenes cause cells to grow out of control. They promote cancer cell growth. Oncogenes are damaged versions of normal genes called proto-oncogenes proto-oncogenesA normal gene involved in the control of cell growth and division that can mutate (change) and become an oncogene. Mutations can be inherited or caused by exposure to a carcinogen (a substance that causes cancer) in the environment. .  A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people. Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes. In some cases, the mutation occurs in a person’s egg or sperm cell but is not present in any of the person’s other cells. In other cases, the mutation occurs in the fertilized egg shortly after the egg and sperm cells unite. Tumor suppressor genes are genes that inhibit cell division, survival, or other properties of cancer cells. Tumor suppressor genes are often disabled by cancer-promoting genetic changes. Typically, changes in many genes are required to transform a normal cell into a cancer cell. Cells often die if they are damaged, through failure of a vital process or the immune system; however, sometimes damage will knock out a single cancer gene. In an old person, there are thousands, tens of thousands or hundreds of thousands of knocked-out cells. Cancer is caused by changes (mutations) to the DNA within cells. The DNA inside a cell is packaged into a large number of individual genes, each of which contains a set of instructions telling the cell what functions to perform, as well as how to grow and divide. Errors in the instructions can cause the cell to stop its normal function and may allow a cell to become cancerous. A gene mutation can instruct a healthy cell to: 1  Allow rapid growth. 2  A gene mutation can tell a cell to grow and divide more rapidly. 3  This creates many new cells that all have that same mutation. 4  Fail to stop uncontrolled cell growth. The initiation of cell transformation is generally associated with genetic alterations in normal cells that lead to the loss of intercellular-and/or extracellular-matrix- (ECM-) mediated cell adhesion. Cancer afflicts an organ or a tissue by inducing abnormal and uncontrolled division of cells that either constitute it or migrate to it. At the cellular level, this is caused by genetic alterations in networks that regulate cell division and cell death. The gene mutations you're born with and those that you acquire throughout your life work together to cause cancer. For instance, if you've inherited a genetic mutation that predisposes you to cancer, that doesn't mean you're certain to get cancer. Instead, you may need one or more other gene mutations to cause cancer. A gene mutation can instruct a healthy cell to: 1  Allow rapid growth. 2  A gene mutation can tell a cell to grow and divide more rapidly. 3  This creates many new cells that all have that same mutation. 4  Fail to stop uncontrolled cell growth. Carcinogenesis or oncogenesis or tumorigenesis is the actual formation of a cancer, whereby normal cells are transformed into cancer cells. Cells often die if they are damaged, through failure of a vital process or the immune system; however, sometimes damage will knock out a single cancer gene. In an old person, there are thousands, tens of thousands or hundreds of thousands of knocked-out cells. Tumors and precancerous lesions are heterogeneous cell populations harboring normal stromal and inflammatory cells. The presence of these cells could mask the detection of genetic and gene expression alterations in the cancer cells. 
http://www.mayoclinic.org/diseases-conditions/cancer/basics/causes/con-20032378 http://www.cancer.ca/en/cancer-information/cancer-101/what-is-cancer/cancer-cell-development/?region=on http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/genemutation https://en.wikipedia.org/wiki/Carcinogenesis http://www.mayoclinic.org/diseases-conditions/cancer/basics/causes/con-20032378 http://www.hindawi.com/journals/ijcb/2012/219196/ http://www.mayoclinic.org/diseases-conditions/cancer/basics/causes/con-20032378 https://en.wikipedia.org/wiki/Carcinogenesis http://molecular-cancer.biomedcentral.com/articles/10.1186/1476-4598-3-9
what causes genetic alterations in normal cells