Colon Cancer (cont.)
Colon Cancer Causes
Most colorectal cancers arise from adenomatous
polyps-clusters of abnormal 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 any of several conditions known as adenomatous polyposis syndromes have a greater-than-normal risk of colorectal cancer.
- In these conditions, numerous adenomatous polyps
develop in the colon, ultimately leading to colon cancer.
- 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
- 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
- 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 that estrogen replacement therapy and nonsteroidal anti-inflammatory drugs such as aspirin may reduce
colorectal cancer risk.
Robert J Fingerote, MD, MSc, BSc
Scott H Plantz, MD, FAAEM
Francisco Talavera, PharmD, PhD
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