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.
Locating the Large Intestine
What is colon cancer?
Cancer Overview of Cancer 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. For example, your intestines have muscle cells to... read more 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 Overview of Cancer 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. For example, your intestines have muscle cells to... read more that starts in the lining of your colon. Rectal cancer is very similar. The two cancers are sometimes referred to as colorectal cancer.
The most common symptoms are bleeding when you pass stool and feeling tired and weak
Everyone over the age of 45 should be screened for colorectal cancer
Colon cancer caught early is more curable
Doctors usually remove the cancer with surgery
What causes colon 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:
Have a colon disease, such as ulcerative colitis Ulcerative Colitis Your digestive tract is the path that food takes through your body after you eat it. Food goes from your mouth (eating) to your anus (passing stool). Your intestine is the long tube in your... read more or Crohn disease Crohn Disease Your digestive tract is the path that food takes through your body after you eat it. Food goes from your mouth (eating) to your anus (passing stool). Your intestine is the long tube in your... read more
Eat a lot of fat, meat, and processed foods and not much fiber
Have family members who have had colorectal cancer or colon polyps
What are the symptoms of colon cancer?
Colon cancer grows slowly and doesn't cause symptoms for a long time. Symptoms may include:
Feeling weak and tired—in some people this is the only symptom
Constipation (trouble passing stool)
Blood in your stool
Feeling like your rectum isn’t completely empty after passing stool
Sometimes the cancer blocks your colon, and you get symptoms of a bowel obstruction Intestinal Obstruction You have a small intestine and a large intestine. The small intestine is a long coiled tube that connects your stomach to your large intestine. The large intestine is shorter but wider and leads... read more , such as throwing up, or having crampy belly pain or a swollen belly.
How can doctors tell if I have colon cancer?
If you have symptoms that doctors think might be from colon cancer, they usually do:
If colonoscopy shows cancer, then doctors usually do:
How do doctors screen for colon cancer?
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 Computed Tomography A CT scan uses a large machine shaped like a large donut to take x-rays from many angles. A computer then takes the x-rays and creates many detailed pictures of the inside of your body. Each... read more to look at your colon after you drink a special fluid and have your colon filled with air, which helps with the imaging)
How do doctors treat colon cancer?
Doctors treat colon cancer with:
Surgery to take out the cancerous part of your colon and join the two cut ends together
In a colostomy, the large intestine (colon) is cut. The part that remains connected to the colon is brought to the skin surface through an opening that has been formed. The part is then stitched to the skin. Stool passes through the opening and into a disposable bag.
For rectal cancer, doctors do:
Surgery to take out part or all of the rectum
Chemotherapy Chemotherapy Chemotherapy is a medicine that destroys cancer cells. Chemotherapy works by shutting down cell growth. But since all cells in the body grow, chemotherapy medicines also destroy some normal... read more plus radiation therapy Radiation Therapy Radiation therapy is a cancer treatment that uses beams of radiation to destroy cancer cells and shrink cancer tumors. Doctors use radiation to treat many types of cancer, including head, neck... read more
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:
CT scan Computed Tomography A CT scan uses a large machine shaped like a large donut to take x-rays from many angles. A computer then takes the x-rays and creates many detailed pictures of the inside of your body. Each... read more or MRI Magnetic Resonance Imaging (MRI) MRI is a test that uses a machine with a powerful magnet to make pictures of the inside of your body. A computer records changes in the magnetic field around your body. The computer then uses... read more