Colon and Rectal Cancers - Symptoms

Risk Factors and Prevention

Colorectal cancer is the third most common cancer in the U.S., with Americans facing a lifetime chance of 5 - 6% for this cancer. Each year, about 143,000 Americans are diagnosed with colorectal cancer, and about 50,000 people die from the disease. About 72% of cancers occur in the colon and 28% in the rectum.

Rates of colorectal cancer have been decreasing in the United States. This is due in part to more people getting regular screenings for colorectal cancer, and fewer people engaging in risk factors such as smoking.

Age

Colorectal cancer risk increases with age. More than 90% of these cancers occur in people over age 50.

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Gender

Men have a slightly higher risk than women for developing colorectal cancer.

Race and Ethnicity

African-Americans have the highest risk of being diagnosed with, and dying from, colorectal cancer. Among Caucasians, Jews of Eastern European (Ashkenazi) descent have a higher rate of colorectal cancer. Asian Americans/Pacific Islanders, Hispanics/Latinos, and American Indians/Alaska Natives have a lower risk than Caucasians.

Family History of Colorectal Cancer

About 20 - 25% of colorectal cancers occur among people with a family history of the disease. People who have more than one first-degree relative (sibling or parent) with the disease are especially at high risk. The risk is even higher if the relative was diagnosed with colorectal cancer before the age of 60.

A small percentage of patients with colorectal cancer have an inherited genetic abnormality that causes the disease. Syndromes associated with genetic mutations include familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer.

• Familial Adenomatous Polyposis (FAP). Familial adenomatous polyposis is caused by mutations in a gene called the adenomatous polyposis coli (APC) gene, which normally helps suppress tumor growth. In its defective form, it accelerates cell growth leading to polyps. The APC mutation can be inherited from either parent. People with FAP develop hundreds to thousands of polyps to in the colon. If FAP is left untreated, virtually everyone who inherits this condition develops cancer by age 45. Polyps usually first appear when people are in their mid-teens. FAP also increases the risks for other types of cancers including stomach, thyroid, pancreatic, liver, and small intestine cancers.
• Hereditary Nonpolyposis Colorectal Cancer (HNPCC). Hereditary nonpolyposis colorectal cancer (HNPCC) is also known as Lynch syndrome.About 50 - 80% of people who inherit the abnormal gene develop colon cancer by age 45. HNPCC is caused by mutations in MLH1, MSH2, MSH6, and PMS2 genes. People with HNPCC are prone to other cancers, including uterine and ovarian cancers, as well as cancers of the small intestine, liver, urinary tract, and central nervous system.