 |
|
| ||||||||||||||||||||||||||
|
|
| ||||||||||||||||||||||||||
|
|
|
|
|
| ||||||||
Colorectal cancer includes cancerous growths in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of death among cancers in the Western world. Many colorectal cancers are thought to arise from polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time. Diagnosis is by colonoscopy. Therapy is usually through surgery, with many cases also requiring chemotherapy.
| Contents |
Symptoms of colorectal cancer include:
Often, the symptoms are much less specific:
It is also possible that there will be no symptoms at all. This is one reason why some recommend periodical screening for the disease.
The lifetime risk of developing colon cancer in the United States is about 7%. Certain factors increase a person's risk of developing the disease. These include:
Colorectal cancer can take many years to develop and early detection of colorectal cancer greatly improves the chances of a cure. Therefore, screening for the disease is recommended in individuals who are at increased risk. There are several different tests available for this purpose.
The pathology of the tumor is usually reported from the analysis of tissue taken from a biopsy or surgery. A pathology report will usually contain a description of cell type and grade. The most common colon cancer cell type is adenocarcinoma which accounts for 95% of cases. Other, rarer types include lymphoma and squamous cell carcinoma.
Cancers on the right side (ascending colon and caecum) tend to be exophytic, that is the tumour grows outwards from one location in the bowel wall. This very rarely causes obstruction of feces, and present with symptoms such as anemia. Left-sided tumours tend to be circumferential, and can obstruct the bowel much like a napkin ring.
Colon cancer staging is an estimate of the condition of a particular cancer for diagnostic and research purposes. The systems for staging colorectal cancers largely depend on the extent of local invasion, the degree of lymph node involvement and whether there is distant metastasis.
The most common currently used system for staging is the TNM system, though many doctors still use the older Duke's system. The TNM system assigns a number:
The stage of a cancer is usually quoted as a number I,II,III,IV derived from the TNM value grouped by prognosis; a higher number indicates a more advanced cancer and a likely worse outcome.
Colorectal cancer is a disease originating from the in epithelial cells lining the gastrointestinal tract. Mutations in specific DNA (particularily the FAP, KRAS and p53 genes) lead to unrestricted cell division. Various causes for these mutations are inborn genetic aberrations, tobacco smoking, environmental, and possibly viral causes. The exact reason why a diet high in fiber prevents colorectal cancer remains uncertain. Chronic inflammation, as in inflammatory bowel disease, may predispose patients to malignancy.
The treatment depends on the staging of the cancer. When colorectal cancer is caught at early stages (with little spread) it can be curable. However when it is detected at later stages (when distant metastases are present) it is less likely to be curable.
Surgery remains the primary treatment while chemotherapy and/or radiotherapy may be recommended depending on the individual patient's staging and other medical factors.
Surgical treatment is by far the most likely to result in a cure of colon cancer if the tumor is localized. Very early cancer that develops within a polyp can often be cured by removing the polyp at the time of colonoscopy. More advanced cancers typically require surgical removal of the section of colon containing the tumor leaving sufficient margins to reduce likelihood of re-growth. If possible, the remaining parts of colon are anastomosed together to create a functioning colon. In cases when anastomosis is not possible, a stoma (artificial orifice) is created. Surgery is generally not offered if significant metastasis are present.
Laparoscopic assist resection of the colon for tumour can reduce the size of painful incision and minimize the risk of infection.
As with any surgical procedure, colorectal surgery can in rare cases result in complications. These may include infection, abscess, fistula or bowel obstruction.
Radiation therapy is used to kill tumor tissue before or after surgery or when surgery is not indicated. Sometimes chemotherapy agents are used to increase the effectiveness of radiation by sensitizing tumor cells if present.
Chemotherapy is used to reduce the likelihood of metastasis developing, shrink tumor size, or slow tumor growth. Chemotherapy is often applied after surgery (adjuvant), before surgery (neo-adjuvant), or as the primary therapy if surgery is not indicated (palliative). The treatments listed here have been shown in clinical trials to improve survival and/or reduce mortality and have been approved for use by the US Food and Drug Administration.
The agents listed here are not proven in clinical trials but may be considered to have anti-colon cancer properties in in-vitro studies, the popular press, folk medicine or other sources.
Cancer diagnosis very often results in an enormous change in the patient's sociological wellbeing. Various support resources are available from, hospitals and other agencies which provide counseling, social service support, cancer support groups, and other services. These services help to mitigate some of the difficulties of integrating a patient's medical complications into other parts of their life.
Most colorectal cancers should be preventable, though increased surveillance, improved lifestyle, and, probably, the use of dietary chemopreventive agents.
| Health science - Medicine - Gastroenterology |
| Diseases of the esophagus - stomach |
| Halitosis - Nausea - Vomiting - GERD - Achalasia - Esophageal cancer - Esophageal varices - Peptic ulcer - Abdominal pain - Stomach cancer - Functional dyspepsia |
| Diseases of the liver - pancreas - gallbladder - biliary tree |
| Hepatitis - Cirrhosis - NASH - PBC - PSC - Budd-Chiari syndrome - Hepatocellular carcinoma - Pancreatitis - Pancreatic cancer - Gallstones - Cholecystitis |
| Diseases of the small intestine |
| Peptic ulcer - Malabsorption (e.g. celiac disease, lactose intolerance, fructose malabsorption, Whipple's disease) - Lymphoma |
| Diseases of the colon |
| Diarrhea - Appendicitis - Diverticulitis - Diverticulosis - IBD (Crohn's disease and Ulcerative colitis) - Irritable bowel syndrome - Constipation - Colorectal cancer - Hirschsprung's disease - Pseudomembranous colitis |
|
||||
| View Live Article | This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License | |
||
