Colon cancer develops from polyps (growths) in your colon’s inner lining. Healthcare providers have screening tests and treatments that detect and remove precancerous polyps. If untreated, colon cancer may spread to other areas of your body. Thanks to these tests, early treatment and new kinds of treatment, fewer people are dying from colon cancer.
Colon (colorectal) cancer starts in your colon (large intestine), the long tube that helps carry digested food to your rectum and out of your body.
Colon cancer develops from certain polyps or growths in the inner lining of your colon. Healthcare providers have screening tests that detect precancerous polyps before they can become cancerous tumors. Colon cancer that’s not detected or treated may spread to other areas of your body. Thanks to screening tests, early treatment and new kinds of treatment, fewer people are dying from colon cancer.
Your colon wall is made of layers of mucous membrane, tissue and muscle. Colon cancer starts in your mucosa, the innermost lining of your colon. It consists of cells that make and release mucus and other fluids. If these cells mutate or change, they may create a colon polyp.
Over time, colon polyps may become cancerous. (It usually takes about 10 years for cancer to form in a colon polyp.) Left undetected and/or untreated, the cancer works its way through a layer of tissue, muscle and the outer layer of your colon. The colon cancer may also spread to other parts of your body via your lymph nodes or your blood vessels.
You can have colon cancer without having symptoms. If you do have symptoms, you may not be sure if changes in your body are signs of colon cancer. That’s because some colon cancer symptoms are similar to symptoms of less serious conditions. Common symptoms of colon cancer include:
• Blood on or in your stool (poop): Talk to a healthcare provider if you notice blood in the toilet after you poop or after wiping, or if your poop looks dark or bright red. It’s important to remember blood in poop doesn’t mean you have colon cancer. Other things — from hemorrhoids to anal tears to eating beets — may change your poop’s appearance. But it’s always better to check with a healthcare provider any time you notice blood in or on your stool.
• Persistent changes in your bowel habits (how you poop): Talk to a healthcare provider if you have persistent constipation and/or diarrhea, or if you feel as if you still need to poop after going to the bathroom.
• Abdominal (belly) pain: Talk to a healthcare provider if you have belly pain with no known cause, that doesn’t go away or hurts a lot. Many things may cause belly pain, but it’s always best to check with a healthcare provider if you have unusual or frequent belly pain.
• Bloated stomach: Like belly pain, there are many things that may make you feel bloated. Talk to a healthcare provider if your bloated belly lasts for more than a week, gets worse or you have other symptoms like vomiting or blood in or on your poop.
• Unexplained weight loss: This is a noticeable drop in your body weight when you’re not trying to lose weight.
• Vomiting: Talk to a healthcare provider if you’ve been vomiting periodically for no known reason or if you vomit a lot in 24 hours.
• Fatigue and feeling short of breath: These are symptoms of anemia. Anemia may be a sign of colon cancer.
Like all types of cancer, colon cancer happens when cells grow and divide uncontrollably. All cells in your body are constantly growing, dividing and dying. That’s how your body remains healthy and working as it should. In colon cancer, cells lining your colon and rectum keep growing and dividing even when they’re supposed to die. These cancerous cells may come from polyps in your colon.
Medical researchers aren’t sure why some people develop precancerous colon polyps that become colon cancer. They do know certain risk factors increase people’s chances of developing precancerous polyps and colon cancer.
Those risk factors include certain medical conditions, including inherited conditions, and lifestyle choices. Having one or more risk factors for colon cancer doesn’t mean you’ll develop the condition. It just means you have increased risk. Understanding risk factors may help you decide if you should talk to a healthcare provider about your risk of developing colon (colorectal) cancer.
Healthcare providers use several tests to diagnose colon cancer. Those tests include:
There are five stages of colon cancer. Three of the four stages have three sub-stages. The colon cancer staging system includes the following:
Stage 0: Healthcare providers may refer to this as carcinoma in situ. When they do, they’re talking about abnormal or precancerous cells in your mucosa, the innermost layer of your colon wall.
Stage I: Stage I colorectal cancer has grown into the wall of your intestine but hasn’t spread beyond the muscular coat or into close lymph nodes.
Stage II: The cancer has spread farther into the wall of your intestine but hasn’t spread to nearby lymph nodes. There are three types of Stage II colon cancer:
Stage III: In this stage, colon cancer has spread to your lymph nodes. Like Stage II colon cancer, there are three sub-stages of Stage III colon cancer:
Stage IV: Cancer has spread (metastasized) to other areas of your body, such as your liver, lungs or ovaries:
Surgery is the most common colon cancer treatment. There are different colon cancer surgeries and procedures:
Healthcare providers may combine surgery with adjuvant therapy. This is cancer treatment done before or after surgery. They may also use these treatments for colon cancer that has spread or come back. Treatments may include:
You may not be able to prevent colon cancer, but you can reduce your risk of developing the condition by managing risk factors:
NCI data shows that overall, 65% of people with colorectal cancer were alive five years after diagnosis. (A survival rate is an estimate based on the experiences of people with specific kinds of cancer.
Colorectal cancer survival rates vary based on the cancer stage at diagnosis. For example, 73% of people with colorectal cancer that’s spread to nearby tissues, organs or lymph nodes were alive five years after diagnosis. That five-year survival rate drops to 17% if the cancer spreads to a distant organ or lymph node.
A survival rate is an estimate based on outcomes — how long people lived after treatment for a specific type of cancer. In this case, survival rates are based on the experiences of large groups of people who have colorectal cancer, and not just colon cancer. In addition, many things affect colon cancer survival rates. If you have this condition, your healthcare provider is your best resource for information about what you can expect.