Colorectal Cancer Defined

by National Institute on Aging

The body is made up of many types of cells. Normally, cells grow, divide, and produce more cells as needed to keep the body healthy and functioning properly. Sometimes, however, the process goes wrong - cells become abnormal and form more cells in an uncontrolled way.

These extra cells form a mass of tissue, called a growth or tumor. Tumors can be benign, which means not cancerous, or malignant, which means cancerous.

Colon, rectum, and other parts of digestive system. Cancer of the colon or rectum is called colorectal cancer. The colon and the rectum are part of the large intestine, which is part of the digestive system. Colorectal cancer occurs when tumors form in the lining of the large intestine, also called the large bowel.

Colorectal cancer is the second leading cause of death from cancer in both sexes in the United States. The risk of developing colorectal cancer rises after age 50. It is common in both men and women.

Sometimes, cancer cells break away from the malignant tumor and enter the bloodstream or the lymphatic system where they travel to other organs in the body. Among other things, the lymphatic system transports white blood cells that fight infection.

When cancer travels or spreads from its original location in the colon to another part of the body such as the liver, it is called metastatic colorectal cancer and not liver cancer. When colorectal cancer does spread, it tends to spread to the liver or lungs.

Today there are more ways than ever to treat colorectal cancer. As with almost all cancers, the earlier it is found, the more likely that the treatment will be successful. If colon cancer is detected in its early stages, it is up to 90 percent curable.

Quiz

1. Cancer is a disease where cells divide and grow normally.

FALSE is the correct answer. Cancer is a disease in which cells become ABNORMAL and keep dividing and forming more cells without order or control. Under the microscope, a cancer cell will usually appear larger and less regular in shape than a normal cell.

2. Colorectal cancer is responsible for fewer deaths each year than any other type of cancer.

FALSE is the correct answer. Colorectal cancer is the second leading cause of death from cancer in both sexes in the United States after lung cancer. The risk of developing colorectal cancer rises after age 50. It is common in both men and women.

3. Metastatic colorectal cancer is cancer that has spread from the colon or rectum to another part of the body.

TRUE is the correct answer. Colorectal cancer may spread to other organs of the body, such as the liver or lungs. When it does this, doctors say it has metastasized. When cancer spreads from its original location in the colon to another part of the body such as the brain, it is called metastatic colorectal cancer, not brain cancer.

4. If colorectal cancer is found early, it is very likely to be cured.

TRUE is the correct answer. Today there are more ways than ever to treat colorectal cancer. As with many cancers, the earlier it is found, the more likely that the treatment will be successful. If colon cancer is detected in its early stages, it is up to 90 percent curable.

Causes and Risk Factors

Scientists don't know exactly what causes colorectal cancer, but they have been able to identify some risk factors for the disease. A risk factor is anything that increases your chances of getting a disease.

Studies show that the following risk factors can increase a person's chances of developing colorectal cancer: age, polyps, diet, personal history, family history, and ulcerative colitis.

Colorectal cancer is more likely to occur as people get older. It is more common in people over the age of 50, but younger people can get it, too. In rare cases, it can occur in adolescence.

Why Get Tested? Polyps are benign, or non-cancerous, growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person's risk of developing colorectal cancer. Not all polyps become cancerous, but nearly all colon cancers start as polyps.

Diet appears to be associated with colorectal cancer risk. Among populations that consume a diet high in fat, protein, calories, alcohol, and both red and white meat, and low in calcium and folate, colorectal cancer is more likely to develop than among populations that consume a low-fat, high-fiber diet.

A diet high in saturated fat combined with a sedentary lifestyle may increase the risk of colorectal cancer. There is also evidence that smoking cigarettes may be associated with an increased risk of colorectal cancer.

Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had colorectal cancer may develop this disease a second time.

The parents, siblings, and children of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves. This is especially true if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.

Ulcerative colitis is a condition in which there is a chronic break in the lining of the colon. Having this condition increases a person's chance of developing colorectal cancer.

Researchers have identified genetic mutations, or abnormalities, that may be linked to the development of colon cancer. They are working to unravel the exact ways these genetic changes occur.

If you have one or more of these risk factors, it doesn't mean you will get colorectal cancer. It just increases the chances. You may wish to talk to your doctor about these risk factors. He or she may be able to suggest ways you can reduce your chances of developing colorectal cancer and plan an appropriate schedule for checkups.

Quiz

1. Polyps are growths in the colon and rectum that are

A. usually benign, which means not cancerous.
B. usually cancerous.
C. rare in people over 50.

A is the correct answer. Polyps of the colon and rectum are usually benign and produce no symptoms, but they may cause painless bleeding from the rectum. There may be single or multiple polyps, and they are fairly common in people over age 50. Over time, certain types of polyps called adenomatous polyps can develop into cancer.

2. Your risk of colorectal cancer goes up if

A. a close family relative such as a sibling, parent, or child has had the disease.
B. you spend too much time in the sun.
C. you give birth to a baby.

A is the correct answer. The parents, siblings, and children of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves. This is especially true if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more. There is no evidence that staying out in the sun or giving birth to a baby causes colorectal cancer.

3. You may reduce your risk factors for colorectal cancer by

A. eating a diet low in saturated fat and increasing the amount of exercise you get.
B. drinking more alcohol.
C. continuing to smoke.

A is the correct answer. A diet high in saturated fat combined with a sedentary lifestyle may increase the risk of colorectal cancer. So, it is probably a good idea to reduce the saturated fat in your diet and get regular exercise to reduce your risk. If you consume high levels of alcohol along with high levels of fat, protein, calories, and both red and white meat, and low levels of calcium and folate, you may increase your risk. Smoking also may put you at higher risk.

4. Having one or more of the risk factors for colorectal cancer means that

A. you will definitely develop the disease.
B. you may want to check with your doctor to discuss the risk factors.
C. you will not develop the disease.

B is the correct answer. If you have one or more of these risk factors, it doesn't mean you will get colorectal cancer. It just increases the chances. You may wish to talk to your doctor about these risk factors. He or she may be able to suggest ways you can reduce your chances of developing colorectal cancer and plan an appropriate schedule for checkups.

About the Author

www.nia.nih.gov
NIA, one of the 27 Institutes and Centers of NIH, leads a broad scientific effort to understand the nature of aging and to extend the healthy, active years of life. In 1974, Congress granted authority to form NIA to provide leadership in aging research, training, health information dissemination, and other programs relevant to aging and older people.