What's in this article?
What is Cancer?
To understand what colon cancer is, it helps to start with a basic understand of cancer in general. Normal cells in the body grow and divide in an orderly fashion. Eventually, they die and are replaced by new, healthy cells. But cancer cells play by different rules they don’t grow in an orderly fashion and they don’t die in an orderly fashion either.
Cancer cells no longer respond to the signals that tell them to grow and divide normally, which allows them to grow out of control. Cancer cells also are ‘immortal’: they have the ability to continue living indefinitely. Even when damaged in a way that should cause cell death, cancer cells may not die.
What is the Colon?
The colon is an important part of the digestive system, and as such, it has a major role in helping the body absorb nutrients, minerals, and water. The colon also helps rid the body of waste in the form of stool. The colon makes up the majority of the large intestine, approximately six feet in length. The last six inches or so of the large intestine are the rectum and the anal canal.
What is Colon Cancer?
Colon cancer is cancer that occurs in the cells of the colon. Colon cancer is quite common, being the third most common cancer in men and women in the U.S. About 110,000 people in the U.S. are diagnosed with colon cancer each year.
Some health experts consider colon and rectum cancers as one group, called colorectal cancer. Others treat these two cancers as completely separate: colon cancer and rectum (rectal) cancer.
Stages of Colon Cancer
In order for your doctor to develop the right treatment plan, he or she will stage your colon cancer. The stage of cancer refers to how far it has spread beyond the location where it first developed in your body.
Generally, the higher the number or letter that is used to describe the stage of cancer, the more advanced the cancer is. To learn more about colon cancer staging, be sure to review Diagnosis of Colon Cancer and Treatment of Colon Cancer.
What are the symptoms of colon cancer?
Cancer symptoms are quite varied and depend on where the cancer is located, where it has spread, and how big the tumor is. It is common for people with colon cancer to experience no symptoms in the earliest stages of the disease. However, when the cancer grows, symptoms include:
- Diarrhea or constipation
- Changes in stool consistency
- Narrow stools
- Rectal bleeding or blood in the stool
- Pain, cramps, or gas in the abdomen
- Pain during bowel movements
- Continual urges to defecate
- Weakness or fatigue
- Unexplained weight loss
- Irritable bowel syndrome (IBS)
- Iron deficiency (anemia)
If the cancer spreads, or metastasizes, additional symptoms can present themselves in the newly affected area. Symptoms of metastasis ultimately depend on the location to which the cancer has spread, and the liver is the most common place of metastasis.
Causes
In most cases, it’s not clear what causes colon cancer. Doctors know that colon cancer occurs when healthy cells in the colon become altered.
Healthy cells grow and divide in an orderly way to keep your body functioning normally. But when a cell is damaged and becomes cancerous, cells continue to divide even when new cells aren’t needed. These cancer cells can invade and destroy normal tissue nearby. And cancerous cells can travel to other parts of the body.
Precancerous growths in the colon
Colon cancer most often begins as clumps of precancerous cells (polyps) on the inside lining of the colon. Polyps can appear mushroom-shaped, or they can be flat or recessed into the wall of the colon. Removing polyps before they become cancerous can prevent colon cancer.
Inherited gene mutations that increase the risk of colon cancer
Inherited gene mutations that increase the risk of colon cancer can be passed through families, but these inherited genes are linked to only a small percentage of colon cancers. Inherited gene mutations don’t make cancer inevitable, but they can increase an individual’s risk of cancer significantly.
The most common forms of inherited colon cancer syndromes are:
- Familial adenomatous polyposis (FAP). FAP is a rare disorder that causes you to develop thousands of polyps in the lining of your colon and rectum. People with untreated FAP have a greatly increased risk of developing colon cancer before age 40.
- Hereditary nonpolyposis colorectal cancer (HNPCC).HNPCC, also called Lynch syndrome, increases the risk of colon cancer and other cancers. People with HNPCC tend to develop colon cancer before age 50.
Treatment
If a diagnosis of colon cancer is made, treatment is determined by the stage of the disease. In other words, earlier stages in which the cancer is small and localized may require less intervention. Typically, surgery can effectively remove small tumors and chemotherapy is prescribed to kill any remaining cells. Chemotherapy drugs commonly used for colon cancer include irinotecan, oxaliplatin, capacitabine and 5-fluorouracil.
More advanced cancers in which the disease has metastasized, or spread, throughout larger areas of the colon or to other parts of the body may require removal of whole sections of the large intestine. Often, the remaining colon can be reconnected to the rectum, but if the cancer has also reached the rectum, a colostomy may be needed. In this procedure, a surgeon creates an opening in the abdomen and attaches a colostomy “bag.” Waste collects in the bag instead of passing through the rectum. Chemotherapy and radiation are then prescribed to kill remaining cancer cells, and control as much as possible the spread of the disease.
