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

Anatomy of the colon

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

Progression of colon polyp to cancer

Most colon cancer start off as benign polyps of the colon. 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 to distant organs. The progression from polyp to invasive cancer usually takes about 10 years, making screening for the disease a life-saving procedure.

Symptoms & Diagnosis

Many people with colon cancer have no symptoms at all. In people who do have symptoms, the most common ones are:

1. Abdominal pain — 44 percent
2. Change in bowel habit — 43 percent
3. Hematochezia or melena — 40 percent
4. Weakness — 20 percent
5. Anemia without other gastrointestinal symptoms — 11 percent
6. Weight loss — 6 percent

References

1. Jemal, A, Siegel, R, Ward, E, et al. Cancer statistics, 2006. CA Cancer J Clin 2006; 56:106.
2. Speights, VO, Johnson, MW, Stoltenberg, PH, et al. Colorectal cancer: Current trends in initial clinical manifestations. South Med J 1991; 84:575.
3. http://www.dana-farber.org/pat/cancer/gastrointestinal/gi-colorectal.asp