How i can say the introduction about colon cancer?

You can introduce colon cancer like the following:

Colon cancer is cancer of the large intestine (colon), the lower part of your digestive system. Rectal cancer is cancer of the last 6 inches of the colon. Together, they're often referred to as colorectal cancers. About 112,000 people are diagnosed with colon cancer annually, and about 41,000 new cases of rectal cancer are diagnosed each year, according to the American Cancer Society.

Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time some of these polyps become colon cancers.

Polyps may be small and produce few, if any, symptoms. Regular screening tests can help prevent colon cancer by identifying polyps before they become cancerous. If signs and symptoms of colon cancer do appear, they may include changes in bowel habits, blood in your stool, persistent cramping, gas or abdominal pain.

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they'll likely vary, depending on the cancer's size and location in your large intestine.

Signs and symptoms of colon cancer include:

* A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool for more than a couple of weeks
* Rectal bleeding or blood in your stool
* Persistent abdominal discomfort, such as cramps, gas or pain
* Abdominal pain with a bowel movement
* A feeling that your bowel doesn't empty completely
* Weakness or fatigue
* Unexplained weight loss

Blood in your stool may be a sign of cancer, but it can also indicate other conditions. Bright red blood you notice on bathroom tissue more commonly comes from hemorrhoids or minor tears (fissures) in your anus, for example. In addition, certain foods, such as beets or red licorice, can turn your stools red. Iron supplements and some anti-diarrheal medications may make stools black. Still, it's best to have any sign of blood or change in your stools checked promptly by your doctor because it can be a sign of something more serious.

In general, cancer occurs when healthy cells become altered. Healthy cells grow and divide in an orderly way to keep your body functioning normally. But sometimes this growth gets out of control 鈥?cells continue dividing even when new cells aren't needed. In the colon and rectum, this exaggerated growth may cause precancerous cells to form in the lining of your intestine. Over a long period of time 鈥?spanning up to several years 鈥?some of these areas of abnormal cells may become cancerous. In later stages of the disease, colon cancer may penetrate the colon walls and spread (metastasize) to nearby lymph nodes or other organs. As with most cancers, the exact cause for colon cancer is unknown.

Precancerous growths in the colon:
Precancerous cells can occur anywhere in your large intestine, the muscular tube that forms the last part of your gastrointestinal tract. The colon comprises the upper 4 to 5 feet of your large intestine, and the rectum makes up the lower 6 inches.

Precancerous growths most commonly occur as clumps of cells (polyps) that extend from the wall of the colon. Polyps can appear mushroom-shaped. Precancerous growths can also be flat or recessed into the wall of the colon (nonpolypoid lesions). Nonpolypoid lesions are more difficult to detect, but are less common.

Several types of colon polyps exist. Among the most common are:

* Adenomas. These polyps have the potential to become cancerous and are usually removed during screening tests such as flexible sigmoidoscopy or colonoscopy.
* Hyperplastic polyps. These polyps are rarely, if ever, a risk factor for colorectal cancer.
* Inflammatory polyps. These polyps may follow a bout of ulcerative colitis. Some inflammatory polyps may become cancerous, so having ulcerative colitis increases your overall risk of colon cancer.

Factors that may increase your risk of colon cancer include:

* Age. About 90 percent of people diagnosed with colon cancer are older than 50. Colon cancer can occur in younger people, but it occurs much less frequently.
* A personal history of colorectal cancer or polyps. If you've already had colon cancer or adenomatous polyps, you have a greater risk of colon cancer in the future.
* Inflammatory intestinal conditions. Long-standing inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase your risk of colon cancer.
* Inherited disorders that affect the colon. Genetic syndromes passed through generations of your family can increase your risk of colon cancer. These syndromes cause only about 5 percent of all colon cancers. One genetic syndrome called familial adenomatous polyposis (FAP) is a rare disorder that causes you to develop thousands of polyps in the lining of your colon and rectum. People with untreated FAP have a greater than 90 percent chance of developing colon cancer by age 45. Another genetic syndrome, hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome, is more common than FAP. People with HNPCC have an increased risk of colon cancer and tend to develop colon cancer at an early age. Both FAP and HNPCC can be detected through genetic testing. Talk to your doctor about whether your family history suggests you have a risk of these conditions.
* Family history of colon cancer and colon polyps. You're more likely to develop colon cancer if you have a parent, sibling or child with the disease. If more than one family member has colon cancer or rectal cancer, your risk is even greater. In some cases, this connection may not be hereditary or genetic. Instead, cancers within the same family may result from shared exposure to an environmental carcinogen or from diet or lifestyle factors.
*Diet. Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. Research in this area has had mixed results. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meats.

People who eat a diet similar to that of Western countries, such as the United States and Europe, have a higher risk of developing colon cancer than do people who eat diets typically seen in developing countries. When people move from a developing country to a Western country and adapt to the Western diet, their risk of colon cancer increases. Although many studies have tried to identify what part of the Western diet may cause colon cancer, the answer remains unknown.

* A sedentary lifestyle. If you're inactive, you're more likely to develop colon cancer. This may be because when you're inactive, waste stays in your colon longer. Getting regular physical activity may reduce your risk.
* Diabetes. People with diabetes and insulin resistance may have an increased risk of colon cancer.
* Obesity. People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight.
* Smoking. People who smoke cigarettes may have an increased risk of colon cancer. They may also have an increased chance of dying of colon cancer.
* Alcohol. Heavy use of alcohol may increase your odds of colon cancer.
* Growth hormone disorder. Acromegaly, an uncommon disorder that causes an excess of growth hormone in your body, may increase your risk of colon polyps and colon cancer.
* Radiation therapy for cancer. Radiation therapy directed at the abdomen to treat previous cancers may increase the risk of colon cancer.

If you notice any symptoms of colon cancer, such as blood in your stool or a persistent change in bowel habits, see your doctor as soon as possible. Keep in mind that colorectal cancer can occur in younger as well as older people. If you're at high risk, don't wait until symptoms appear. See your doctor for regular screenings.

Talk to your doctor about when you should begin screening for colon cancer. Guidelines generally recommend colon cancer screenings begin at age 50. Your doctor may recommend more frequent or earlier screening if you have other risk factors, such as a family history of the disease.

Screening and diagnosis:

Screening
Most colon cancers develop from adenomatous polyps. Screening can detect polyps before they become cancerous. Screening may also detect colon cancer in its early stages when there is a good chance for cure.

You may be embarrassed by the screening procedures, worried about discomfort or afraid of the results. Discuss your screening options and your concerns with your doctor. Most procedures are only moderately uncomfortable, and working with a doctor you like and trust can help ease your embarrassment.

If you need further information about colon cancer, you could visit the following website:

www.mayoclinic.com

Colorectal cancer is a term used to refer to cancer that starts in either the colon or the rectum. Colon cancer and rectal cancer have many features in common. They are discussed together here except for the section about treatment, where they are discussed separately.

The normal digestive system

Colon and rectal cancers begin in the digestive system, also called the GI (gastrointestinal) system (see the picture below). This is where food is processed to create energy and rid the body of solid waste matter (stool). In order to understand colorectal cancer, it helps to know some basics about the normal structure and function of the digestive system.

After food is chewed and swallowed, it travels down to the stomach. There it is partly broken down and sent to the small intestine. The word "small" refers to the width of the small intestine. In fact, the small intestine is the longest part of the digestive system -- about 20 feet.

The small intestine also breaks down the food and absorbs most of the nutrients. The small intestine leads to the large intestine (also called the large bowel or colon), a muscular tube about 5 feet long. The colon absorbs water and nutrients from the food and also serves as a storage place for waste matter. The waste matter moves from the colon into the rectum, the last 6 inches of the digestive system. From there the waste passes out of the body through the opening called the anus.

The wall of the colon and rectum has several layers of tissues. Colorectal cancer starts in the inner layer and can grow through some or all of the other layers. Knowing a little about these layers is helpful because the stage (extent of spread) of a cancer depends to a great degree on how deep the cancer goes into these layers.

Abnormal growths in the colon or rectum

Cancer that starts in these different areas may cause different symptoms. But colon cancer and rectal cancer have many things in common. In most cases, colorectal cancers develop slowly over many years. We now know that most of these cancers begin as a polyp--a growth of tissue that starts in the lining and grows into the center of the colon or rectum. This tissue may or may not be cancer. A type of polyp known as an adenoma can become cancerous. Removing a polyp early may prevent it from becoming cancer.

Over 95% of colon and rectal cancers are adenocarcinomas. These are cancers that start in the cells that line the inside of the colon and rectum. There are some other, more rare, types of tumors of the colon and rectum, but the facts given here refer only to adenocarcinomas.

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