User:Palmd/colonca
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Overview
Colon cancer is the third most common caner in both men and women in the United States. It is the second-leading cause of cancer-related deaths in the U.S, with 50,000-60,000 people dying of it yearly.
Anatomy
The anantomy of the colon is important in understanding cancer. The colon is usually considered to have 5 sections:
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
Cancers arising in different parts of the colon can cause different symptoms, and can metastasize, or spread, differently. Of special importance, cancers of the rectum have greater potential to spread to several parts of the body at once, while cancers from the rest of the colon tend to spread first to the nearby lymph nodes, and then to the liver.
Natural History & Prevention
Most colon cancer start off as benign colon polyps. As these polyps grow, the cells in them can become abnormal, and eventually cancerous. At some point after that, they can gain the ability to invade the rest of the body and spread (or metastasize) to distant organs. The progression from polyp to invasive cancer usually takes about 10 years, making screening for the disease a life-saving procedure.
Most colon cancers arise after the age of 50, at which time screening is recommended. There are, however, several inherited types of colon cancer, the most important of which are hereditary nonpolyposis colorectal cancer (HNPCC) and Familial adenomatous polyposis (FAP). People with these conditions require earlier and more frequent screening. Also, people with Ulcerative Colitis are very susceptible to colon cancer and must be screened early and often.
Symptoms & Diagnosis
Many people with colon cancer have no symptoms at all. In people who do have symptoms, the most common ones are:
- Abdominal pain — 44 percent
- Change in bowel habit — 43 percent
- Hematochezia or melena — 40 percent
- Weakness — 20 percent
- Anemia without other gastrointestinal symptoms — 11 percent
- Weight loss — 6 percent
Treatment & Prognosis
References
- Jemal, A, Siegel, R, Ward, E, et al. Cancer statistics, 2006. CA Cancer J Clin 2006; 56:106.
- Speights, VO, Johnson, MW, Stoltenberg, PH, et al. Colorectal cancer: Current trends in initial clinical manifestations. South Med J 1991; 84:575.
- http://www.dana-farber.org/pat/cancer/gastrointestinal/gi-colorectal.asp