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Causes - Early Symptoms - Advanced Stages - Colon
Cancer
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Colon Cancer and Colorectal Cancer - Causes - Symptoms - Diagnosis - Treatment
Colon and Colorectal Cancer To understand colorectal or colon cancer you must first know what cancer is. Simply put, cancer is a malignant tumor and colon cancer is a malignant tumor of the colon. Colorectal cancer is a malignancy of the rectum. Cancer comprises a broad group of malignant neoplasms (abnormal formations of tissue such as growths or tumors) that can be divided into two groups: carcinoma and sarcoma. Carcinomas originate in the epithelial tissues (the layer of cells forming the epidermis of the skin and the surface layer of mucous and serous membranes) while sarcomas develop from connective tissues (the tissues that had their origin in mesodermal tissues). The mesoderm is a primary germ layer of the embryo from which all connective tissues arise; muscular, skeletal, circulatory, lymphatic. Both types of tumors are invasive and tend to metastasize to new sites. They both spread directly into surrounding tissues and may be distributed through the lymphatics or circulatory system. To further understand these diseases you must first understand
what the colon is. The colon is the large intestine from the end of
the ileum to the rectum. It is divided into the ascending, transverse,
descending, and the sigmoid (pelvic) colon (see illustration). The mechanical
function of the colon is to mix the the intestinal contents. In Western countries, colon and rectal malignancies account for more new cases per year than any other part of the body except the lung. In the USA, about 75,000 people died of these malignancies in 1989. About 70% of these malignancies of the intestine occurred in the rectum and sigmoid intestines, and 95% were adenocarcinomas. Adenoma is a neoplasm of glandular epithelium and adenocarcioma is a malignant adenoma. Colorectal malignancies are the most frequent cause of death among visceral malignancies (malignancies of internal organs) that affect both sexes. The incidence begins to rise at age 40 and peaks at 60 to 75 years of age. Most people are unaware that malignancies of the intestines are more common in women. However, malignancies of the rectum are more common in men. It's also worthy of mention that five percent of patients will possess more than one malignancy. Risks The risk of genetic predisposition to a malignant disease of the large intestine is very low. However it can occur in families over several generations. They usually occur by the age of 40. Populations with a high incidence of this type of malignancy eat low-fiber diets that are high in animal protein, animal fat, and refined sugars. Changing to a high-fiber diet with less animal protein and fat and less refined carbohydrates may lower the risk. Symptoms and Signs Intestinal malignant tumors usually develop slowly, and a long time passes before it is large enough to produce symptoms. Early diagnosis depends on routine examination. Symptoms depend on where it is located, the type of tumor or mass, the extent or spread of the disease, and any complications. The right colon is large in diameter and has a thin wall. Some tumors may grow large enough to be palpable (perceptible by touch) through the abdominal wall. Bleeding is usually occult (obscured or concealed). Fatigue and loss of strength caused by severe anemia may be the only complaints. The left colon has a smaller lumen (the opening inside the intestine) and malignancy in this area tends to encircle the bowel (intestine), causing alternating constipation and diarrhea with increased frequency of bowel movements. Partial or complete obstruction with abdominal pain can be the presenting symptoms. The stool may bemixed with blood or streaked with blood. In malignant conditions of the rectum, the most commonly seen symptom is bleeding in the stool. Therefore, when rectal bleeding occurs malignancy of the intestinal organs or rectum must be suspected and ruled out even if there is a known case of diverticular disease or obvious hemorrhoids present. Diagnosis and Detection Simple testing of the stool for occult blood is advised if a malignancy is suspected. The patient should eat a high-fiber diet without red meat for 3 days before having their stool tested for occult blood. If there is a positive test further studies should be performed. Fiberoptic colonoscopy (examination of the upper portion of the rectum with a colonoscope or long speculum) should be performed when a malignancy is suspected in any portion of the intestine (bowel) and when symptoms pertain to the intestinal organ. If a lesion or polyp is detected on sigmoidoscopy, a colonoscopy and complete removal of all lesions should be performed. If a lesion is not removable during colonoscopy, surgical excision (cutting the lesion out) should be seriously considered. Barium enema x-ray examination is often unreliable to detect a rectal malignancies but may be an important preliminary step to diagnose this type of malignant condition. Barium should not be given orally when an obstructing intestinal lesion is suspected, because it may end up producing a complete obstruction of the large intesting. It should be noted that barium enemas miss about 30% to 40% of tumors and polyps. Treatment and Prognosis Treatment methods for colon cancer include surgery, chemotherapy, radiation therapy, immunotherapy, vaccine therapy or a combination of these therapies. Primary treatment consists of surgical resection (excision or cutting out a wide tissue area) of the problem area. Surgical resection for a rectal cancerous disease depends on the tumor's distance from the anus and the extent of the malignant growth. Surgical cure is possible in approximately 70% of these patients with intestinal malignancies. When the patient is an unacceptable surgical risk, some tumors can be controlled by electrocoagulation (a high frequency electrical current that produces heat in the infected tissue to be destroyed). Colorectal cancer patients with as many as four positive lymph nodes derive most benefit from combined radiotherapy (radiation) and chemotherapy (applying chemical reagents to the disease-causing organisms that have a specific and toxic effect upon them). When more than four lymph nodes are affected these two combined treatment methods are not as effective. When surgery does not cure the condition, palliative surgery (attempting to reduce the symptoms) may be indicated. The only drug with proven efficacy for an advanced colorectal cancer is 5-FU, but only 15 to 20% of patients receiving 5-FU show a shrinking of the tumor and the prolonging of life. A new drug, irinotecan, appears to have possibilities as a single agent with the advanced disease and will be evaluated as part of a combination treatment (chemotherapy and radiotherapy). Colon Cancer Screening and Prevention When rectal bleeding occurs malignant tumors of the intestinal organs or rectum must be ruled out even if there are obvious hemorrhoids or a known case of diverticular disease. If you have any symptoms of this disease you should see a doctor. More than 90% of these victims are older than 50 so if you're past 50 years of age it would be a good idea to get screened for it. Increased risk is linked to low-fiber diets that are high in animal protein, animal fat, and refined carbohydrates. It may be beneficial to change eating habits if this is the case. Obese people have a higher malignancy risk so losing weight would be a good preventative measure. Polyps A polyp (a clinical term without any pathologic significance) is a mass of tissue that arises from the intestinal wall and protrudes into the lumen (the space inside of the intestine). Incidence of polyps range from about 7 to about 50 percent. The higher percentage includes very small polyps found at autopsy. Polyps, often multiple, occur most commonly in the rectum (the last portion of the large intestine) and sigmoid organ and decrease in frequency toward the cecum (the beginning portion of the large intestine). Most polyps are asymptomatic (they have no symptoms or signs). When symptoms are present he most common one is rectal bleeding. A large polyp, or lesion, may produce cramps, abdominal pain or obstructions. Rectal polyps may be palpable (perceptible by touch) during examination, but usually are discovered by endoscopy (inspection of body organs with the use of an endoscope). Because rectal polyps are often multiple and may coexist with cancer, complete colonoscopy is necessary. On barium enema x-rays, a polyp appears as a rounded filling defect. Fiberoptic colonoscopy is a reliable diagnostic tool. Polyps in children are usually non-neoplastic, often outgrow their blood supply, and autoamputate (spontaneous amputation of a part) at puberty. Treatment is required only for uncontrollable bleeding or intussusception (the slipping of one part of an intestine into another part just below it). Hyperplastic (excessive proliferation of normal cells) polyps are common in the intestines and rectum. Inflammatory polyps and pseudopolyps (hypertrophied areas of mucous membranes resembling polyps) occur in chronic ulcerative colitis (ulcers and inflammation in the intestinal organs) and in Crohn's disease (inflammation of the intestines) of the intestines. Treatment of Polyps Polyps should be removed completely. Treatment of a cancerous polyp depends on the depth of invasion and other factors. The excision of polyps without a clear resection line or a poorly differentiated masses or lesions should be followed by intestinal segmental resection.
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