The Gastrointestinal System - Term Paper Example

? GASTROINTESTINAL CANCER Institute The gastrointestinal system is an important system of the human body which is essential for the performance of normal bodily functions. Cancer can arise in the different parts of the gastrointestinal system which include the esophageal cancer, gastric cancer, liver cancer, gall bladder cancer, pancreatic cancer, colon cancer and anal cancer. Different types of cancers can occur in these organs. Adenocarcinoma and squamous cell carcinoma are the different types of cancers of the oesophagus. Risk factors of the oesophageal cancers include alcohol consumption and tobacco smoking. Different types of gastric cancer include carcinoma, lymphoma, carcinoids and stromal tumours. Helicobacter pylori are infective organisms which have been linked with the gastric cancer. Colorectal cancer is associated with genetic mutations as well low fibre diets and diets which lack essential vitamins. Gastrointestinal Cancer Cancer is uncontrolled and abnormal growth of a tissue destroying the adjacent tissues also. Sometimes the cancer metastasize which means the spread of cancerous cells from one part of the body to other part of the body through blood or lymph fluid. These properties of cancer make it more dangerous than benign tumours because benign tumours do not attack the nearby tissue and thus do not destroy them and benign tumours do not metastasize. Cancer cells have self sufficiency in growth, self replicative, insensitive to antigrowth signals and avoid apoptosis. Gastrointestinal system is a complex system which breaks and digests the ingested food mechanically and with the help of enzymes. Cancer can occur in gastrointestinal system too like esophageal cancer, gastric cancer, liver cancer, gall bladder cancer, pancreatic cancer, colon cancer and anal cancer. Esophageal cancer is condition in which the cells of esophagus start reproducing abnormally in uncontrolled way which destroys the esophagus. The cancer in esophagus mostly occurs in epithelial cells which lines the surface of esophagus. There are two types of esophageal cancer: squamous cell carcinoma and adenocarcinoma. The squamous cell carcinoma mostly occurs in those populations which excessively consume alcohol, tobacco and hot tea. Adenocarcinoma is that cancer of esophagus which occurs in higher socioeconomic class, or in population with obesity and gastroesophageal reflux disease. Generally squamous cell carcinoma occurs due to the irritation in esophageal squamous epithelium. The risk factors for the development of squamous cell carcinoma are tobacco, alcohol, high starch and low fibres diet, achalasia and a few more. Excessive tobacco use is can cause esophageal squamous cell carcinoma. If a person smoke cigarette or use smokeless tobacco products the effect of tobacco causing squamous cell carcinoma remain the same. Chronic alcohol use is also cause of development of esophageal squamous cell carcinoma. The quitting of use of tobacco and alcohol decrease the risk of development of esophageal squamous cell carcinoma. Unbalance diet is also increase the risk of development of squamous cell carcinoma. Diet rich in starch and having low quantity of fibres aid in development of esophageal squamous cell carcinoma. Squamous cell carcinoma occurs in patient with previous achalasia. Chronic irritants of the esophagus, Plummer-vinson syndrome increase the risk of squamous cell carcinoma. Adenocarcinoma occurs in patients with gastroesophageal reflux disease and Barrette’s disease history. Barrette’s disease is the metaplasia of epithelial cells of esophagus. Metaplasia is the reversible change of cells which are replaced by another type of adult cells. In Barrette’s disease normal stratified squamous epithelium of distal esophagus is replaced by coloumnar epithelium containing goblet cells. The development of adenocarcinoma from Barrette’s esophagus is a long process which takes years to occur. The degree at which change in the cells occurs is responsible for development of adrenocarcinoma. If the degree of dysplasia is too low in a patient then the patient is less prone to the progression of adenocarcinoma. The metaplasia occurs due to continuous injury to the esophageal epithelium in gastroesophageal reflux disease. The metaplastic columnar epithelium predisposes the patient to the dysplasia and in last adenocarcinoma. The signs and symptoms of esophageal cancer are dysphagia and odynophagia. Dysphagia means difficulty in swallowing and odynophagia means painful swallowing. Pain in epigastrium is also a symptom of esophageal cancer. Severe heartburn is seen in esophageal cancer. Abnormal peristalsis is observed which causes nausea, vomiting and regurgitation of food. Blood in vomiting is characteristic of esophageal cancer. Gastric cancer is of different types like carcinoma, lymphoma, carcinoids and stromal tumours. The most important and common type of cancer of stomach is carcinoma having percentage of 90 to 95. 4% of the gastric cancers are lymphomas, 3% are carcinoids and 2% stromal cancer. Gastric carcinoma is very fatal and it is the second leading reason for the deaths caused by the cancers in world nowadays. The survival rate of gastric carcinoma is only 5 years. The morphology of gastric cancers shows two types intestinal gastric cancer and diffuse gastric cancer. Intestinal gastric cancer is the one which arise from the gastric mucosal cells in which metaplasia has been occurred and causing severe gastric inflammation. The intestinal gastric cancer is more common. The diffuse type of gastric cancer arises in gastric mucosal cells by abnormal growth of the mucosal cells. In diffuse type of gastric cancer do not cause gastric inflammation. The intestinal type of gastric cancer occurs chiefly in male and the after the age of about 50 years. The diffuse gastric cancer occurs in early ages in females mostly. The gastric carcinoma occurs in pylorus and antrum of stomach about 50 to 60 percent and 25% occurs in cardia. The lesser curvature of stomach is the most ideal location for gastric carcinoma to occur. The causes of gastric carcinoma are Helicobacter pylori bacteria, smoked food and smoking etc. Helicobacter pylori is a gram negative rod type of bacteria which binds to the gastric mucosa and cause damage in the gastric mucosa. Ammonia is produced from urea by urease and this excessive ammonia is responsible for the damage of gastric mucosa and inflammation. The ammonia neutralizes the gastric acids which makes it easy for the bacteria to live for longer interval of time. Destruction of protective mucosal coat of gastric mucosa leads to gastritis and ulcers. The gastritis usually goes along with gastric atrophy and metaplasia which eventually leads to dysplasia and carcinoma. The mechanism of developing gastric cancer in individuals with gastritis caused by helicobacter pylori bacteria is not clearly known but it is said that inflammation caused by helicobacter pylori bacteria release reactive oxygen species which results in the damage of DNA (deoxyribonucleic acid). This DNA damage disturbs the balance in cell proliferation and destruction which occurs in tissue repair site. Due to this abnormal growth of the cells of gastric mucosa starts and results in carcinoma of stomach. Smoking also increases the risk for the development of gastric cancers. Gastric cancers generally have no symptoms but in advanced stages of gastric cancer some symptoms can appear. In advanced stages of gastric cancers abdominal pain, nausea and vomiting, diarrhoea, blood in stool and vomiting are observed. Unusually dysphagia is seen in some patients. The most common treatment of gastric cancer is the removal of the specific part of stomach or whole stomach to remove all the cancerous cells. Endoscopic mucosal resection EMR is surgery for mucosal cancer cells removal. Endoscopic submucosal dissection ESD is the surgery for removal of large part of stomach. Colorectal cancer is cancer of colon and rectum which is also known as bowel cancer. The colorectal cancer mostly occurs in age above 60 years. The development of colorectal cancer is influenced by genetic factors and environmental factors. Genetically, germ line mutations of DNA mismatch repair genes causes a syndrome known as hereditary nonpolyposis colorectal cancer syndrome (HNCCS). This syndrome is also known as Lynch syndrome. Persons with Lynch syndrome have increased risk of development of colorectal cancer and other tumours. Environmental factors that increases the risk of development of colorectal cancer are dietary factors for example low vegetable fibres diet, increased amount of refined carbohydrates, low intake of vitamins A, C and E and high fat diet. The development of colorectal cancer has two pathways, the APC/?-catenin pathway and the mismatch repair pathway. The first pathway also called as adenomacarcinoma sequence has chromosomal instability causing mutation of oncogenes and tumour suppressor genes. The second pathway also known as microsatellite instability pathway is characterized by the lesions in DNA mismatch repair genes. (MSH2, MSH6, MLH1, PMS1, and PMS2) these are the five DNA mismatch repair genes. Mutation in any one of these five DNA mismatch repair genes leads to Lynch syndrome in a person due to which the risk for development of colorectal cancer increase to a high level. In this pathway simple repetitive DNA is formed due to loss of DNA mismatch repair genes loss. These simple repititve DNA is known as microsatellite. Both the pathway eventually leads to colorectal cancer. Person with colorectal cancer shows no symptoms for many years. Fatigue, weakness, iron deficiency anaemia, occult bleeding, changes in bowel habits, bowel obstruction, decreased appetite, weight loss and many more. Colorectal cancer can be diagnosed by digital rectal examination and fecal occult blood test. The main treatment of colorectal cancer is surgery. Surgically all the cancerous cells are removed. Chemotherapy is done to decrease the spread of cancer in unaffected part of colon or other part of gastrointestinal tract. Conclusion: Cancer is lethal and destructive disease characterized by uncontrolled abnormal growth of cells which destroy the organ. Cancer can also attack the gastrointestinal system. The gastrointestinal system is made up of different organs starting from oral cavity and ending at anus. Every organ can be attacked by cancer as a result of which the organ is destroyed and other bodily functions are also disturbed e.g. liver and pancreas cancer because liver and pancreas play major roles in different body functions. Cancers may arise in the oesophagus, stomach as well as the colon and the rectum. There are different types of cancers which affect these organs and they can be associated with different causes which include the usage of tobacco and tobacco for oesophageal cancer. Infective organisms like H. Pylori can result in gastric cancer and low fibre diet along with genetic mutations can lead to colorectal cancers. Surgical treatment as well as chemotherapy is the treatment used for curing these pathologies. References Hunter, J. G., Thomas, C. R., & Jobe, B. A. (2009).Esophageal cancer: Principles and practice. New York: Demos Medical Pub. Top of Form Kumar, V., Abbas, A. K., Fausto, N., Robbins, S. L., & Cotran, R. S. (2005). Robbins and Cotran pathologic basis of disease. Philadelphia: Elsevier Saunders. Bottom of Form Mohan, Harsh.(2005) Textbook of Pathology. New Delhi: Jaypee Bros. Read More