Colorectal Cancer

What Is It?

Colorectal cancer is a type of uncontrolled growth of abnormal cells that can develop in the colon, rectum or both. Together the colon and rectum make up the large intestine (large bowel). The large intestine carries the remnants of digested food from the small intestine and eliminates them as waste through the anus.

Colorectal tumors begin as polyps (small growths) on the inside of the large intestine. Polyps that aren't removed eventually can become cancerous, penetrate through the wall of the colon or rectum, and spread to other areas.

Colorectal cancer is a common type of cancer in the United States. It is the second most common cause of death from cancer in the country. The American Cancer Society estimates that 145,000 new cases of colorectal cancer will have been diagnosed in 2005, and about 56,000 people in the United States will have died of this disease.

Risk Factors The older you get, the more likely you are to develop colorectal cancer. Other factors that increase the risk of developing colorectal cancer include:

• Family history - Heredity may play a role in up to 10% of all cases of colorectal cancer. Genetic defects have been linked to a number of cancer syndromes that run in families and make family members more likely to develop polyps and colorectal cancer.

• A personal history of the disease - If you have been diagnosed with colorectal cancer once, you have an increased risk of developing the disease again.

• A personal history of adenomatous polyps - A personal history of polyps also increases the risk.

• Inflammatory bowel disease (chronic ulcerative colitis, Crohn's disease) - The longer and more severely the colon is inflamed, the greater the risk of cancer.

• Poor diet - Diets low in fiber and high in fat, especially saturated fat, may increase the risk of colorectal cancer.

• A sedentary lifestyle - Among people who exercise regularly, the risk of colon cancer is reduced by half. Even regular brisk walking may reduce a person's risk of developing colon cancer.

• Race and ethnicity - Different racial and ethnic groups in the United States have very different rates of colorectal cancer. Alaska natives are most likely to develop the disease, while Hispanics and Filipinos are the least likely. Whites and African-Americans fall somewhere in between.

Symptoms

Precancerous polyps and early colorectal cancer generally don't cause symptoms. More advanced cancer can cause any of the following symptoms.

• A change in bowel habits

• Diarrhea or constipation

• Blood in the stool (bright red, black or very dark)

• Narrowed stools (about the thickness of a pencil)

• Bloating, fullness or stomach cramps

• Frequent gas pains

• A feeling that the bowel does not empty completely

• Weight loss without dieting

• Continuing fatigue