Colorectal Cancer Info > Colon Polyps and CancerColon Polyps and Cancer
Cancer of the colon is a major health
problem in the United States, ranking as one of the most prevalent forms of
cancer, along with lung cancer and breast cancer. Importantly, colon cancer is
also one of the most treatable forms of cancer. When detected early more than 90
percent of patients can be cured.
This disease begins in the cells that line the colon. There now is strong
medical evidence that there are abnormal genes that can influence the
development of colon polyps and cancer, and that these genes can be hereditarily
passed from parent to child. The genes within each cell are the hereditary
structures that tell the cell what it should do. When normal controlling genes
are absent there is a tendency to grow polyps. The cells in the polyp eventually
become uncontrolled and turn into a cancer. Colon cancer also can develop with
other conditions, such as ulcerative colitis, a chronic inflammation in the
colon.
What Is
It? | What Causes It?
| Who Is At Risk? | Detection | Summary
What
is a Colon Polyp?
A polyp is a growth, or fleshy tumor that occurs in
the colon or other organs. These growths are shaped like a mushroom or a
dome-like button, and occur on the inside lining of the colon. They may be as
small as a tiny pea, or larger than a plum. Colon polyps start out as benign
tumors but in time may become malignant.
A great
deal is known about why and how polyps form. In some people, heredity and genes
are the most important factors. In others, heredity may be a contributing
factor, but diet and foods may also be very important.
- Heredity and Genes
Within certain family histories only the
physician can properly advise you. In some families the genetic disorder is so
strong that it is the only thing that matters. Hereditary Familial Polyposis and
Lynch Syndrome are two disorders that are clearly linked to genes alone. For the
vast majority of polyps, dietary and genetic influences may be of equal
importance. The data is not entirely clear but the medical evidence strongly
suggests this.
- Diet
There are literally thousands of chemicals and substances in
the foods we eat. Each person eats different types and amounts of food, so doing
medical studies to determine which are important is difficult. Nevertheless,
certain substances have been found to be important.
A free radical is a natural byproduct of normal metabolism. Free radicals may
cause damage within the body. Fruits and vegetables have great quantities of
antioxidants, chemicals that neutralize the free radicals. Animal foods do not
contain antioxidants. People who eat diets rich in fruits and vegetables seem to
have a lower incidence of many cancers including colon cancer. The
recommendation is to eat five portions of colorful fruits and/or vegetables each
day. Vitamin C, E, and betacarotene supplements have not been shown to prevent
any cancer.
- Calcium
Calcium in some way regulates the growth of the cells that
line the inside of the colon. This may be why medical studies are beginning to
show that people who get 1000 - 1500 mg of calcium a day in their diet have less
colon cancer. This level of calcium (from milk, dairy products, vegetables, or
supplements) is currently recommended for healthy bones. It may also benefit the
colon.
- Meat and saturated fat
Saturated fat may be broken down in the
body to carcinogens which, at least in animals, can lead to colon cancer.
Saturated fat is found in many prepared foods such as pastries and sauces, and
in meats. A significant reduction in saturated fat intake is recommended for
many health benefits.
- Fiber
Studies years ago did relate a very high fiber diet in rural
Africans to reduced intestinal problems such as diverticulosis and colon cancer.
A recent analysis of the eating habits of over 100,000 American nurses showed
that fiber, up to 25 grams a day, by itself, was not protective against this
cancer. However, most fruits and vegetables are high in fiber and also contain
beneficial chemicals called antioxidants.
In summary, a diet high in fruits, vegetables and calcium, and low in
saturated fats and meats offers the best protection against colon cancer and
many other cancers.
- Three Categories of polyps
Enough is now known about polyps that
physicians generally place patients in one of three categories. In each of these
the end result is an adenoma-type polyp:
- The ordinary polyp - Most sporadic polyps occur in patients between the ages
of 40 and 60. There is a hereditary link. There may be only one or two present
and they may take 10 years or more to develop into a cancer.
- Hereditary Familial Polyposis - This is a true hereditary condition in which
the entire colon is studded with hundreds, even thousands of polyps. They begin
at a very early age even sometimes found in patients under ten years old.
Virtually every patient will eventually develop colon cancer. The only known
preventive treatment is surgical removal of the colon. Fortunately, the
condition is not common.
- Lynch Syndrome (Hereditary Non-Polyposis Colorectal Cancer) - This disorder
is more common than familial polyposis but less so than the ordinary polyp.
There is a strong tendency for adenoma type polyps to occur in close blood
relatives such as sisters, brothers, aunts, uncles, and children. More polyps
are seen and at an early age. Polyps and even cancer occur at earlier ages,
often found in patients in their 40's, 30's, and even in the 20's. In some
families, there is also an increased incidence of breast, ovarian, and other
cancers. So a family history of this type warrants very close surveillance of
all direct blood relatives.
The key to early detection of colon polyps
and cancer is the concern and willingness of each person to seek medical
attention from a physician. The physician generally will perform the following:
- Medical history - The patient's medical history will identify the presence
of risk factors for colon polyps and cancer.
- Stool exams to detect occult (hidden) blood - Colon cancers and large polyps
may shed minute quantities of blood so examination of the stool for occult blood
is an important exam.
- Sigmoidoscopy - This is a visual exam of the rectum and lower colon using a
lighted flexible endoscope. It allows for the direct detection of colon tumors.
- Colonoscopy - This procedure examines the entire 5 - 6 foot long colon. The
exam is usually done under sedation. It is really the definitive exam since
colon polyps can be discovered and removed at the same time.
- Barium enema - This x-ray exam is an older exam which at times is still
useful. Barium flows into the colon and x-rays are taken which then can outline
the shadows of polyps and cancer. Polyps cannot be removed by this technique.
Cancer of the colon is a serious but
readily detected malignancy. Early detection promises a particularly high chance
of survival. Most colon cancers start as polyps, which can usually be removed
through a colonoscopic exam. Today, there is much that can be done to prevent
and cure this cancer. The essential first step involves action by the patient.