Tennessee Wesleyan College
November 13, 2013
Cancer is the result of abnormal cells growing out of control. Normally cells will grow, divide, and then die. Cancer cells in comparison rapidly divide when an issue in the DNA occurs; instead of dying the cancerous cells continue to grow to form new abnormal cells. These cancer cells also invade other tissues which is something normal cells cannot do (American cancer society). Select forms of cancer will give rise to tumors while others invade the blood or blood-forming organs which circulate throughout the body. Cancer, when spreading, travels through the body by the blood and lymph system where the tumors form. “The [creeping]-like invasion of cancer into healthy tissue and the migration of cancer cells to sites distant from the primary tumor” (Murphy P. 2001) poses serious threats to the body. Tumors may eventually take over the normal tissues surrounding the tumor. Breast cancer, as the name implies, usually begins either in the cells of the lobules (milk producing glands) or the ducts (the passage that drains milk from the lobules to the nipples.) (breastcancer.org). Breast cancer can be either invasive or non-invasive. Invasive means that the cancer has grown into normal, healthy tissues. Non-invasive cancers will stay inside the lobules or milk duct in the breast.
Very early types of breast cancers are called ductal carcinoma in situ (DCIS). This is when cancer cells are found in the ducts but have not yet developed the ability to spread (Pennery and others 2009). Not all breast cancers grow or behave the same way, such as invasive ductal carcinoma and inflammatory breast cancer. Invasive ductal carcinoma will have tumors present and inflammatory breast cancer will not have tumors present. “Approximately 5% of breast cancers do appear to occur due to an inherited genetic abnormality in an autosomal dominant manner with incomplete penetrance.” (Barber and others 2008). Across a women’s lifetime she has a one in nine chance of developing breast cancer, in younger women, the chances are much less to get breast cancer. Up to the age of 30; however, females have only a one in 1,900 chance of getting breast cancer. (Pennery and others 2009) Genes associated with inherited breast cancer are the BRCA1 (Breast/Ovarian cancer risk 1) gene on the 17th chromosome and the BRCA2 (Breast/Ovarian cancer risk 2) on the 13th chromosome. A mutation on the BRCA1 gene confers a lifetime risk of breast cancer of around 75%, in addition to an increased risk of ovarian, prostate, and colon cancer. Disease onset with mutated BRCA1 is typically at a relatively early age. A mutation on the BRCA2 gene results in a lifetime risk of breast cancer of around 60%, again with disease onset at a relatively early age. The risk of ovarian cancer is also increased. Unknown to most, cases of male breast cancers are common (Barber and others 2008). Also, other mutations on genes CDH1, STK11, and TP53 can have an increased effect on a person’s risk of acquiring breast cancer. “The ATM and CHEK2 genes have the strongest evidence of being related to the risk of developing breast cancer. The TP53 (tumor protein p53) gene is located on the 17th chromosome short arm 13th banding region 0.1sub banding region (17p13.1) and is 19,148 base pairs long. The TP53 gene is a tumor suppressor that regulates cell division by keeping the cells from growing and dividing out of control. TP53 is located in the nucleus of cell and if DNA becomes damaged the TP53 can repair the DNA. TP53 will activate and regulate in order to repair the DNA; if the DNA cannot be repaired the TP53 will keep the cell from dividing. If changes occur to TP53 gene the risk of developing breast cancer greatly increases as part of rare inherited cancer syndrome called Li-Fraumeri syndrome. “Somatic mutations in the TP53 gene are much more common, occurring in approximately 20 percent to