There are two main types of genes that play a role in cancer: oncogenes and tumor suppressor genes. Proto-oncogenes are regular genes that can become oncogenes if mutated and an oncogene is a gene that can lead to a tumor when mutated because it causes cells to divide unrestrainedly (Heidi 2008). On the contrary, tumor-suppressor genes slow down cell division. When tumor-suppressor genes do not function properly, cells can grow as rapidly as an oncogene (Heidi 2008). Tumor-suppressor genes involve the BRCA1 and BRCA2 genes that are found in breast cells (Klugar & Park 2013). Certain mutations in each can increase the risk of ovarian or pancreatic cancer (Klugar & Park 2013).
Most breast cancers are inherited, but they can also be acquired. Unlike proto-oncogenes, the American Cancer Society’s article on cancer states that most of the tumor-suppressor gene mutations are acquired instead of inherited. Acquired mutations of the TP53 gene code for the p53 protein and they appear in a variety of cancers, such as lung and breast cancer ("Oncogenes, tumor suppressor," 2011). Cells with damaged DNA continue to divide and eventually leading to cancer if the gene for the p53 protein is not properly functioning ("Oncogenes, tumor suppressor," 2011).
The risk of having breast cancer increases when there is a family history of breast cancer. For example, a woman who has a sister or mother with breast cancer is more likely to develop the disease herself because the genetic mutation is inherited (Klugar & Park 2013). According to the American Cancer Society, 5% to 10% of all cancers are from hereditary mutations. This means that some people are more likely to develop cancer than others because they are born with mutations in their genes.
Other factors that can increase the risk of breast cancer are radiation or chemical-induced mutations. Radiation-induced mutations, which are ultraviolet rays from the sun, or X-rays are absorbed by bases in DNA and change the bonds (Phelan 2010). On the other hand, chemical-induced mutations, such as chemicals from cigarette smoke, can also change DNA molecules and at some point result in any form of cancer (Phelan 2010).
BRCA genetic testing has some advantages and disadvantages. The advantages of BRCA genetic testing is that a woman can detect early in time whether her result is positive or negative and can reduce the risk of developing cancer by taking prescription medicine (Hartmann 2014). Like Jolie, if a woman tests positive for the BRCA gene, then she may consider prophylactic surgical removal of her breasts before cancer has an opportunity to form. After having the double mastectomy, Jolie’s doctor calculated that her cancer risk dropped from 87% to 5% (Klugar & Park 2013). This can also be a disadvantage of...