Colon Cancer: Symptoms, Treatment, and Causes - Research Paper Example

 Colon Cancer: Symptoms, Treatment, and Causes Introduction Colon cancer, which is also known as colorectal, or bowel cancer, is a cancer that results from uncontrolled growth of cells in the rectum, colon or the appendix; studies have also proved that the rectal cancer is the same as colon cancer (Adrouny, 2002). Colon cancer is mainly caused by lifestyle of individuals and their age, poor lifestyles and eating habits especially those in the developed world lead to the increased risk of getting colon cancer, in addition, individuals who are advanced in their age, from 50 years are also at a higher chance of contracting the disease. Colon cancer usually starts to develop at the lining of the bowel and if not detected it grows to the muscles below the lining and further extends to the bowel wall, this cancer can be detected through the process of sigmoidoscopy or colonoscopy. Colon cancer is the third most prevalent type of cancer with about 60 per cent of reported cases happening in the developed world. Colon cancer is curable if detected early through surgery and removal of the affected parts otherwise if it has advanced it is incurable and the only remedy that is available is chemotherapy to prolong and improve the quality of life. This research paper will study colon cancer in detail including its signs and symptoms, causes, pathogenesis, diagnosis, prevention, management, prognosis and epidemiology. Signs and symptoms Colon cancer has varied signs and symptoms depending on its location in the large intestines, however, several signs and symptoms are common, they include: increased constipation, narrowing of stool, unnecessary loss of appetite, loss of weight, blood stains in stool, general weakness and feeling tired often, and feeling the urge to relieve oneself which is not actualised (Allman, 2012). Causes of colon cancer Most of the cases of colon cancer occur in individuals who have no genetic risk of the disease, some of the risk factors that contribute to the development of colon cancer include the following; old age, being of the male gender and taking alcoholic beverages. In addition, lack of enough physical exercise, excessive uptake of fats contained in food, smoking, eating red meat and being obese increase the risk of developing colon cancer. 1. Inflammatory bowel disease Individuals who have inflammatory bowel disease, which include ulcerative colitis and Crohon’s disease have a higher risk of getting colon cancer, the risk increases with the length that an individual has had the infection and the severity of the infection. In preventing the infection, treatment with aspirin and colonoscopies is recommended (Ruggieri & Tolentino, 2012). However, individuals with the inflammatory bowel disease account for less than two per cent of all colon cancer cases annually. In individual with Crohon’s disease, the risk of getting colon cancer is 2 per cent after 10 years, 8 per cent after 20 years and 18 per cent after 30 per cent while in those individuals who have ulcerative colitis the chances of developing cancer is 16 per cent after 30 years 2. Genetics Individuals who have first-degree relatives with colon cancer disease are three times more likely to develop the disease as compared to those who do not have first-degree relatives with the disease. Colon cancer cases that are as a result of genetic inheritance account for about 20 per cent of the total cases of colon cancer. In addition, several genetic disorders also increase the chances of an individual contracting colon cancer; some of those disorders are hereditary such as nonpolyposis colorectal cancer (HNPCC) which accounts for about 3 per cent of all colon cancer cases. Gardner syndrome and Familial adenomatous polyposis are other genetically inherited diseases that cause colon cancer and account for only 1 per cent of all colon cancer cases. A large number of deaths that result from colon cancer are as a result of metastatic disease that is caused by a gene that influences the expression of hepatocyte growth factor, the gene is responsible for proliferation, invasion and scattering of cancerous cells. 3. Epigenetics Epigenetic mutations are more likely to cause colon cancer than genetic mutations, it is estimated that on average, colon cancer has one or two oncogene mutations and one to five tumour suppressor mutations with other passenger mutations exceeding that number by up to 10 times. The epigenetic mutations in colon cancer affect a large number of genes, for instance, the microRNA which are about 22 nucleotides long which do nor code for protein but target the protein coding cells and reduce their expression, expression of these microRNA’s can be genetically altered. For instance, epigenetic alteration of involving CpG methylation of DNA encoding miR-137, which is a frequent symptom of early colon cancer development, it appears in 81 per cent of all colon cancer cases. In addition to the epigenetic alteration of miRNA’s, other epigenetic alterations that lead to the development of colon cancer due to reduction in gene expression include hypermethalation or hypomehylation of CpG islands of protein encoding genes and alterations in histones and chromosomal architecture that influence gene expression. Recent studies have also indicated that a reduction in DNA repair gene and enzymes lead to manifestation of genomic and epigenomic traits of colon cancer Pathogenesis Colon cancer is a cancerous defect that originates from epithelial lining of the colon or rectum in the digestive tract due to mutations in the Wnt signalling pathway, which leads to artificial increase in the signalling activity where the mutations are either inherited from relatives or acquired from the environment (Gearhart &Ahuja, 2011). The APC gene, which produces the APC protein, is the most mutated gene that mainly occurs in the intestinal stem crypt cells, this APC protein acts as an inhibitor to the production of β-catenin, the mutations in the APC production leads to accumulation of the β-catenin until it starts to move to the nucleus. In the nucleus, it binds DNA and leads to activation of genes that are usually responsible for the stem cell renewal and differentiation but when they increase above certain levels, they lead to growth of cancerous cells. For a cell to develop to a cancerous cell there must be other mutations apart from those that occur in the Wnt, APC and DNA pathway, the P53 protein that is secreted by TP53 gene controls cell divisions and kills any cells that are found to have any cancer causing defects. With time a TP53 gene is mutated which leads to transformation of tissues from adenoma to an invasive carcinoma, sometimes, however it is not the TP53 cells that mutate but other protective protein such as BAX Other proteins that are deactivated in the process of colon cancer formation include TGF-β and DCC (Deleted in Colon Cancer); in Colon cancer, TGF-β is usually deactivated in almost all the cases of colon cancer, however, sometimes it is the downstream SMAD protein that is deactivated, DCC protein has its chromosome deleted in colon cancer (Bub, Rose and Wong, 2008). Some of the genes in the rectum and colon are oncogenes in colon cancer meaning that they are over expressed, genes such as KRAF, PI3K and RAF, which are normally responsible for cell division as a mechanism of replacing the torn out cell or due to growth of an individual may mutate due to over activation of cell proliferation. The order in which the mutations take place is important in determining the likelihood of development of cancer, if a KRAS mutation occurs first then it leads to development of a tumour that limits itself to the extent that it can develop. If APC mutation occurs first then the KRAS mutation occur, then the likelihood of developing colon cancer is increased significantly; PTEN, which is a lesion suppressor, helps in reducing PI3K from cell division although sometimes it is also deactivated or mutated leading to reduction of its efficiency. Field cancerization is a term that is used to describe an area in the epithelium that has been made by largely unknown factors to be likely affected by cancerous cells; they are the malignant tissues where cancer is likely to start. Most of the studies that have been done in colon cancer have been in developed tumours but there is evidence that over 80 percent of all cancer developments occur before the final form of cancer that is externally expressed develops, that is to mean that the process of cancer formation starts long before it can be detected in the cells. Diagnosis Diagnosis of colon cancer is done by tumour biopsy through the process of colonoscopy or sigmoidoscopy depending on where the cancer is located, the extent of the spread of the cancer is then determined through a CT scan, however, in special circumstances technologies such as MRI and PET may be used The histology of the cancerous tumour is reported from the analysis of the tissue that is gotten from the biopsy or surgery and a pathological report is made which includes the type of cells and the grade; the most common type of colon cancer cells is the adenocarcinoma, other forms of colon cancer cells include lymphoma and squamous cell carcinoma. Colon cancer that develops on the right side of the gastrointestinal tract tend to be exophytic meaning that they grow outwards from the bowel wall, cancer that develops on the left side is usually surround the inner wall of the tract causing the stool that is excreted to be narrow. Adenocarcinoma, which is the most often found cancerous cell in the gastrointestinal tract, comes from the glandular epithelium of the colorectal mucosa, and invades the walls infiltrating in to the muscularis mucosae, submucosa and then muscularis proprian where the tubular tumour cells harbour pluristratification, multiple lumens and reduced stroma. Prevention of colon cancer Since most of the cases of colon cancer are caused by environmental and lifestyle factors, it is therefore easy to prevent the development of most of the colon cancer cases; some of the ways that can be used to reduce the risk of developing cancer include the following 1. Lifestyle Since a large number of colon cancer cases are as a result of poor lifestyles, the risk of colon cancer can be reduced by observing healthy diet that include increasing consumption of whole grain meals, fruits and vegetables. In addition reducing the consumption of red meat, regular exercise and physical activities also significantly reduce the risk of colon cancer (Yang, 2010). 2. Screening Most of the colon cancer cases arise from the adenomatous polyps, which are visible through screening, this makes it easier for the detection of the development of cancer two to three years before the physical signs and symptoms manifest themselves, this can therefore reduce the number of deaths by up to 60 per cent (Yarbro, Wujcik & Gobel, 2010) The three main types of cancer screening tests that are carried out include faecal occult blood testing, flexible sigmoidoscopy and colonoscopy where3 only sigmoidoscopy cannot test colon cancer in the right hand side. In the recent past another test, M2-PK test, where the enzyme M2-PK has been identified with colon cancer and polyps, this test just requires a small sample of the stool and no prior preparation is required before taking the test (Cappell, 2008). 3. Medication Aspirin and celecoxib have been associated with reducing the risk levels of individuals who are in high risk of developing colon cancer however not recommendable for those with average risk of developing the disease. Management Management of people with colon cancer rely on several considerations that include level of advancement of colon cancer or the preference of the individual. For the individual who have localised cancer, surgery is the best alternative where the area that is affected is removed together with a safe margin. Chemotherapy can also be used in addition to surgery in order to increase the life expectancy of the individual or suppress the tumours before a surgery to remove the timorous cells. Radiations can also be used to kill the cancerous cells in the case of the rectal malignant cells, however, if the cancer has developed in the colons, this procedure not advisable due to bowel sensitivity to radiations. Conclusion The symptoms of colon cancer vary depending on the location of the disease in the gastrointestinal tract especially between the rectum and the colon; this can be explained by the different causes of colon cancer that ranges from epigenetics, genetic mutations and inflammatory bowel disease. Cancer development starts in the epithelial lining of the colon or the rectum due to mutation of Wnt signalling pathway, the development is accelerated by deactivation of cancer prohibiting enzymes and activation of enzymes that accelerate growth of cancerous cells, these cancerous cells can be diagnosed through colonoscopy or sigmoidoscopy. Since most of colon cancer cases are as a result of lifestyle, it can be treated or managed through early screening, adopting healthy lifestyles such as regular exercise and balanced diet, in addition, surgery of the affected part may also work to remove cancerous cells in the gastrointestinal tract. References Adrouny, A. R. (2002). Understanding colon cancer. Jackson: University Press of Mississippi. Allman, T. (2012). Colon Cancer. Detroit: Lucent Books. Bub, D.S, Rose, S. & Wong, W D. (2008). 100 Questions & Answers About Colorectal Cancer. Sudbury, Mass: Jones and Bartlett Publishers. Cappell, M.S. (2008). Colon Cancer Screening, Surveillance, Prevention and Therapy. Philadelphia, Pa: Saunders. Gearhart, S. & Ahuja, N. (2011). Colon Cancer. Philadelphia, Pa: Saunders. Ruggieri, P. & Tolentino, A.R. (2012) Colon & Rectal Cancer: From Diagnosis to Treatment. Omaha, Neb: Addicus Books. Yang, V.W. (2010). Colon Cancer: an Update and Future Directions. New York: Elsevier. Yarbro, C.H, Wujcik, D. & Gobel ,B.H. (2010). Cancer Nursing: Principles and Practice. Sudbury, MA: Jones and Bartlett Publishers. Read More