Your colon is your large intestine. Your rectum is a pouch at the end of your colon where stool is stored until you pass it.
Cancer is the out-of-control growth of cells in your body. Cells are the tiny building blocks of your body. Cells specialize in what they do. Different organs are made of different kinds of cells. Almost any kind of cell can become cancerous.
Colon cancer is cancer that starts in the lining of your colon. Rectal cancer is very similar. The two cancers are sometimes referred to as colorectal cancer.
Colorectal cancer is caused by the out-of-control growth of cells in the lining of your colon or rectum. You're more likely to get colorectal cancer if you:
Colon cancer grows slowly and doesn't cause symptoms for a long time. Symptoms may include:
Sometimes the cancer blocks your colon, and you get symptoms of a bowel obstruction, such as throwing up, or having crampy belly pain or a swollen belly.
If you have symptoms that doctors think might be from colon cancer, they usually do:
Colonoscopy, also called a lower endoscopy
If colonoscopy shows cancer, then doctors usually do:
Because colon cancer is so common, doctors recommend screening tests to look for cancer before it causes symptoms. Screening for colon cancer usually begins at age 45 but earlier if you have certain high risk factors. Talk to your doctor about when you need to start screening.
Screening tests include:
Testing your stool for blood you can't see
Sigmoidoscopy (doctors use a flexible viewing tube inserted through your anus to look at the lower part of your large intestine)
Colonoscopy (to have a more complete view of the intestine than is possible with sigmoidoscopy, doctors thread a thin, lighted tube with a small camera through your anus to look at all of your colon)
CT colonography (CT scan to look at your colon after you drink a special fluid and have your colon filled with air, which helps with the imaging)
Doctors treat colon cancer with:
Surgery to take out the cancerous part of your colon and join the two cut ends together
Sometimes, chemotherapy after surgery
For rectal cancer, doctors do:
If doctors have to take out your rectum, you usually will need a colostomy. With a colostomy, doctors attach the end of your colon to an opening in the wall of your belly. Your stool comes out of this opening into a plastic colostomy bag. The bag is stuck onto your belly with adhesive and you change it when it fills up.
After your treatment, doctors will continue to care for you and check on your health with regular testing, such as: