What is colon cancer?

Colon cancer occurs when abnormal cells grow out of control in the lower part of your intestine (your colon).

If the tumor was small and had not spread, your doctor may have removed it during the colonoscopy. But you may need surgery to remove the cancer if the tumor was too big or had spread too far to be removed during a colonoscopy. If cancer has spread to another part of your body, such as the liver, you may need surgery or other treatments.

Treatment for colon cancer may also include radiation therapy and medicines that destroy cancer cells (chemotherapy). In some cases, targeted therapy or immunotherapy may be an option.

Colon cancer usually grows very slowly. It usually takes years for the cancer to become large enough to cause symptoms. If the cancer is not removed and keeps growing, it eventually will invade and destroy nearby tissues and then spread farther, first to nearby lymph nodes. From there it may spread to other parts of the body.

Colon cancer in its early stages usually doesn't cause any symptoms. Symptoms occur later, when the cancer may be harder to treat. The most common symptoms include:

• Blood in your stool or very dark stools.
• A change in your bowel habits, such as more frequent stools or a feeling that your bowels are not emptying completely.
• Pain in the belly or rectal pain.
• Low energy.

Treatment for colon cancer is based on the stage and location of the cancer. It's also based on other things, such as your overall health. Most people have surgery to remove the cancer. Chemotherapy, radiation therapy, or both may also be used. In some cases, targeted therapy or immunotherapy may be an option.

Screening tests can find or prevent many cases of colon cancer. They look for a certain disease or condition before any symptoms appear.

Screening tests that may find colon cancer early include:

• Stool tests, such as the fecal immunochemical test or the guaiac fecal occult blood test.
• Sigmoidoscopy, which lets your doctor look at the inside of the lower part of your colon using a lighted tube.
• Colonoscopy, which lets your doctor look at the inside of your entire colon using a thin, flexible tube.

Your risk for colorectal cancer gets higher as you get older. Experts recommend starting screening at age 45 for people who are at average risk. Talk with your doctor about your risk and when to start and stop screening.

People with a higher risk, such as those with a strong family history of colon cancer, should be tested earlier than those with an average risk.

Here are other things you can do to help prevent colon cancer:

• Watch your weight. Being very overweight may increase your chance of getting colon cancer.
• Eat well. Eat more whole grains, fruits, vegetables, poultry, and fish. And eat less red meat, refined grains, and sweets.
• If you drink alcohol, limit how much you drink. Any amount of alcohol may increase your risk for some types of cancer.
• Get active. Keep up a physically active lifestyle.
• Quit smoking. If you smoke cigarettes, quit smoking to reduce your chance of getting colon cancer.

• Take your medicines exactly as prescribed. Call your doctor if you think you are having a problem with your medicine.
• Follow your doctor's instructions to relieve pain. Pain from cancer and surgery can almost always be controlled. Use pain medicine when you first notice pain, before it becomes severe.
• Eat healthy food. If you do not feel like eating, try to eat food that has protein and extra calories to keep up your strength and prevent weight loss. Drink liquid meal replacements for extra calories and protein. Try to eat your main meal early.
• Get some physical activity every day, but do not get too tired.
• Take steps to manage your stress, such as learning relaxation techniques. To also help reduce stress, get enough sleep, eat a healthy diet, and take time to do things you enjoy.
• Think about joining a support group. Or discuss your concerns with your doctor or a counselor.
• If you are vomiting or have diarrhea:
  • Drink plenty of fluids to prevent dehydration. Choose water and other clear liquids. If you have kidney, heart, or liver disease and have to limit fluids, talk with your doctor before you increase the amount of fluids you drink.
  • When you are able to eat, try clear soups, mild foods, and liquids until all symptoms are gone for 12 to 48 hours. Other good choices include dry toast, crackers, cooked cereal, and gelatin dessert, such as Jell-O.
• If you have not already done so, prepare a list of advance directives. Advance directives are instructions to your doctor and family members about what kind of care you want if you become unable to speak or express yourself.

Colon cancer happens when cells that are not normal grow in your colon. These cells often form in polyps, which are small growths in the colon. Not all colon polyps turn into cancer. But most colon cancer starts in a polyp.

Colon cancer occurs most often in people older than 50.