Colon Cancer

What Is Colon Cancer?

Colon cancer is a common type of malignancy (cancer) in which there is uncontrolled growth of the cells that line the inside of the colon or rectum. Colon cancer is also called colorectal cancer.

  • The colon, also known as the large intestine, is the last part of the digestive tract.
  • The rectum is the very end of the large intestine that opens at the anus.

Understanding Cancer

The body is made up of different types of cells that normally divide and multiply in an orderly way. These new cells replace older cells. This process of cell birth and renewal occurs constantly in the body.

Cancer or malignant growths occur when:

  • Some cells in the body begin to multiply in an uncontrolled manner.
  • The body’s natural defenses, such as certain parts of the immune system, cannot stop uncontrolled cell division.
  • These abnormal cells become greater and greater in number.
  • In some types of cancer, including colon cancer, the uncontrolled cell growth forms a mass, also called a tumor.

Some tumors are benign, which means that they are not cancerous. Cancerous or malignant tumors grow out of control and can invade, replace, and destroy normal cells near the tumor. In some cases, cancer cells spread to other areas of the body.

There are two kinds of growths that occur in the colon:

  • noncancerous growths, such as polyps.
  • Malignant or cancerous growths. Colon cancer usually begins with the growth of benign growths such as polyps.

Most types of colorectal cancer are adenocarcinomas. This means that the cancer cells are formed from abnormal gland cells that line the inner surface of an organ. The prefix “adeno” means “gland.” In colorectal cancer, the abnormal growth begins to form in the inner lining of the large bowel.

Nice To Know:

Other forms of colon cancer may occur, but are not nearly as common as adenocarcinomas.

  • Tumors that begin in connective tissue, such as sarcomas
  • Tumors that begin in the lymphatic system, such lymphomas
  • Rare cancers such as carcinoids and gastrointestinal stromal tumors.

If a polyp develops and is not removed, it may become cancerous. Once a cancer develops it begins to invade the intestinal wall and may spread to nearby lymph nodes. Lymph nodes are part of the lymphatic system, which carries special filtered fluids throughout the body. Through the lymphatic system, cancer cells may also be carried to areas of the body far away the original tumor.

This process of cancer cells traveling to other parts of the body is known as metastasis. The spread of cancer may also occur via the blood stream. Colon and rectal cancers that metastasize through the blood stream will travel first to the liver. There the cancerous cells may continue to grow and develop new tumors. As these new tumors continue to grow and spread further, the function of vital organs, such as the liver, may deteriorate.

About The Digestive System

The digestive system receives food, breaks it down into smaller, useful nutrients, absorbs these nutrients into the bloodstream, and eliminates the remaining waste from the body.

The digestive system is made up of

  • The esophagus
  • The stomach
  • The small intestine
  • The large intestine, also known as the colon <

The colon has several parts:

  • Ascending colon – Beginning in the lower right abdomen and continuing up the right side.
  • Transverse colon – Beginning at the upper right side of the abdomen and continuing across to the left side of the abdomen.
  • Descending colon – From the left upper abdomen straight down to the left lower side.
  • Sigmoid colon – An S-shaped section that leads downward into the pelvic cavity.
  • Rectum – The last six or so inches of the colon, ending at the anus.

Facts About Colon Cancer

  • About 150,000 new cases of colorectal (colon and rectal) cancer are diagnosed each year in the U.S., making it the second most common type of cancer and the second leading cause of cancer death in the U.S.
  • One-third of all colorectal cancers are found in the rectum; the rest are found in other parts of the colon.
  • Screening for colorectal cancer should begin at the age of 40 in healthy adults. Seventy to 80 percent of colorectal cancer cases occur in adults without specific risk factors.
  • Widespread screening for colorectal cancer could save up to many lives each year.
  • Early detection reduces the probability of major surgery and increases chances of cure.
  • The risk of colon cancer increases after age 40.
  • Both men and women are equally at risk for colorectal cancer.
  • In the U.S. the death rate for colorectal cancer is declining. This may be due to a higher rate of screening for the disease.
  • Colon cancer may affect any racial or ethnic group; however, some studies suggest that Americans of northern European heritage have a higher-than-average risk of colon cancer.


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