Colon Cancer (cont.)
Colon Cancer Causes
Most colorectal cancers arise from adenomatous polyps. Such polyps are comprised of excess numbers of both normal and abnormal appearing cells in the glands covering the inner wall of the colon. Over time, these abnormal growths enlarge and ultimately degenerate to become adenocarcinomas.
People with certain genetic abnormalities develop what are known as familial adenomatous polyposis syndromes. Such people have a greater-than-normal risk of colorectal cancer.
- In these conditions, numerous adenomatous polyps develop in the colon, ultimately leading to colon cancer.
- There are specific genetic abnormalities found in the two main forms of familial adenomatous polyposis.
- The cancer usually occurs before age 40 years.
- Adenomatous polyposis syndromes tend to run in families. Such cases are referred to as familial adenomatous polyposis (FAP). Celecoxib (Celebrex) has been FDA approved for FAP. After 6 months, celecoxib reduced the mean number of rectal and colon polyps by 28% compared to placebo (sugar pill) 5%.
Another group of colon cancer syndromes, termed hereditary nonpolyposis colorectal cancer (HNPCC) syndromes, also run in families. In these syndromes, colon cancer develops without the precursor polyps.
- HNPCC syndromes are associated with a genetic abnormality. This abnormality has been identified, and a test is available. People at risk can be identified through genetic screening.
- Once identified as carriers of the abnormal gene, these people require counseling and regular screening to detect precancerous and cancerous tumors.
- HNPCC syndromes are sometimes linked to tumors in other parts of the body.
Also at high risk for developing colon cancers are people with any of the following:
The risk of colon cancer increases 2-3 times for people with a first-degree relative (parent or sibling) with colon cancer. The risk increases more if you have more than one affected family member, especially if the cancer was diagnosed at a young age.
Other factors that may affect your risk of developing a colon cancer:
- Diet: Whether diet plays a role in developing colon cancer remains under debate. The belief that a high-fiber, low-fat diet could help prevent colon cancer has been questioned. Studies do indicate that exercise and a diet rich in fruits and vegetables can help prevent colon cancer.
- Obesity: Obesity has been identified as a risk factor for colon cancer.
- Smoking: Cigarette smoking has been definitely linked to a higher risk for colon cancer.
- Drug effects: Recent studies have suggested postmenopausal hormoneestrogen replacement therapy may reduce colorectal can cer risk by one third. Patients with a certain gene which codes for high levels of a hormone called 15-PGDH may have their risk of colorectal cancer reduced by one half with the use of aspirin.
Medically Reviewed by a Doctor on 8/13/2015
Robert J Fingerote, MD, MSc, BSc
Scott H Plantz, MD, FAAEM
Francisco Talavera, PharmD, PhD
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