Polyps can occur anywhere in your large intestine, the muscular tube that forms the last part of your gastrointestinal (GI) tract. The colon comprises the upper 4 to 6 feet of your large intestine, and the rectum makes up the lower 8 to 10 inches. Your colon absorbs water, salt and other minerals from food and stores waste until it's eliminated from your body. Polyps may be small and produce few, if any, symptoms, so it's important to get regular screening tests to help prevent colorectal cancer. If signs and symptoms of cancer do appear, they may include a change in bowel habits, blood in your stool, persistent cramping, gas or abdominal pain.

Polyps are either mushroom-shaped or flat and may be large or small. There are also several different types of colon polyps. 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. Often less than 1/4 inch in diameter, these polyps are rarely, if ever, a risk factor for colorectal cancer.

• Inflammatory polyps. These polyps may follow a bout of ulcerative colitis. Although the polyps themselves aren't a significant risk, having ulcerative colitis increases your overall risk of colon cancer.

Still, there's good news about colorectal cancer. Screening tests, along with a few simple changes in your diet and lifestyle, can dramatically reduce your overall risk of developing the disease.

In general, colon rectum cancers have significant abnormal blood vessels denoting the presence of significant amounts of VEGF (vascular endothelial growth factor), which is a prerequisite for cancer metastasis or further growth.  Knowing this, monoclonal antibody drugs are available against VEGF (e.g., bevacizumab).

Signs and Symptoms

Like many people with colorectal cancer, patients may have no symptoms in the early stages of the disease. When symptoms appear, they will likely vary, depending on the cancer's size and location in your large intestine.

In some cases, symptoms may result from a condition other than cancer, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and sometimes diverticulosis or diverticulitis. Like colorectal cancer, these conditions are treatable.

If any of the following signs and symptoms persist for more than a couple of weeks, it is imperative that people see their doctors immediately:

• A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool
• Narrow, pencil-thin stools
• Rectal bleeding or blood in your stool on more than one occasion
• Persistent abdominal discomfort, such as cramps, gas or pain
• A feeling that your bowel doesn't empty completely
• 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 may come 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 one’s physician.

Risk Factors

Colorectal cancer can occur at any age, and no one is too young to develop colorectal cancer. However, about 90 percent of people with the disease are older than 50. Factors other than age that place you at a higher risk include:

• Inflammatory intestinal conditions. Long-standing inflammatory diseases of the colon, such as ulcerative colitis and Crohn's disease, can increase a person’s risk.

• Family history. If many family members have colon or rectal cancer, a person’s risk is even greater. In some cases, this connection isn't hereditary or genetic. Instead, cancers within the same family may result from shared exposure to an environmental carcinogen or from diet or lifestyle factors:

o Familial adenomatous polyposis (FAP) is a rare hereditary disorder that causes hundreds of polyps to develop in the lining of the colon and rectum, beginning in the adolescent years. If these go untreated, a person will likely develop colon cancer by age 40.

o Hereditary nonpolyposis colorectal cancer (HNPCC) is another hereditary disorder that can put a person at high risk of developing colon or rectal cancer. Unlike FAP, however, the colon and rectum may have relatively few polyps.

• Diet. Colorectal cancer may be associated with a diet low in fiber and high in fat and calories. Research is still occurring in this area. However, high-fiber, low-fat diets have additional health benefits apart from a potential connection to colorectal cancer prevention.

• Living the lazy life. Inactivity will more likely increase the risk of developing colon cancer, although not rectal cancer. When a person is inactive, waste stays in the colon longer. Getting regular physical activity may reduce one’s risk of colon cancer.

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