Colon cancer is a growth of cells that begins in a part of the large intestine called the colon. The colon is the first and longest part of the large intestine. The large intestine is the last part of the digestive system. The digestive system breaks down food for the body to use.
Colon cancer typically affects older adults, though it can happen at any age. It usually begins as small clumps of cells called polyps that form inside the colon. Polyps generally aren't cancerous, but some can turn into colon cancers over time.
Polyps often don't cause symptoms. For this reason, doctors recommend regular screening tests to look for polyps in the colon. Finding and removing polyps helps prevent colon cancer.
If colon cancer develops, many treatments can help control it. Treatments include surgery, radiation therapy and medicines, such as chemotherapy, targeted therapy and immunotherapy.
Colon cancer is sometimes called colorectal cancer. This term combines colon cancer and rectal cancer, which begins in the rectum.
Many people with colon cancer don't have symptoms at first. When symptoms appear, they'll likely depend on the cancer's size and where it is in the large intestine.
Symptoms of colon cancer can include:
If you notice lasting symptoms that worry you, make an appointment with a health care professional.
Doctors aren't certain what causes most colon cancers.
Colon cancer happens when cells in the colon develop changes in their DNA. A cells' DNA holds the instructions that tell the cell what to do. The changes tell the cells to multiply quickly. The changes let the cells continue living when healthy cells die as part of their natural lifecycle.
This causes too many cells. The cells might form a mass called a tumor. The cells can invade and destroy healthy body tissue. In time, the cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer.
Factors that may increase the risk of colon cancer include:
Doctors recommend that people with an average risk of colon cancer consider starting colon cancer screening around age 45. But people with an increased risk should think about starting screening sooner. People with an increased risk include those with a family history of colon cancer.
There are several different tests that are used for colon cancer screening. Talk about your options with your health care team.
Making changes in everyday life can reduce the risk of colon cancer. To lower the risk of colon cancer:
Some medicines can reduce the risk of colon polyps or colon cancer. For instance, some evidence links a reduced risk of polyps and colon cancer to regular use of aspirin or aspirin-like medicines. But it's not clear what dose and what length of time would be needed to reduce the risk of colon cancer. Taking aspirin daily has some risks, including ulcers and bleeding in the digestive system.
These options are generally reserved for people with a high risk of colon cancer. There isn't enough evidence to recommend these medicines to people who have an average risk of colon cancer.
If you have an increased risk of colon cancer, discuss your risk factors with your health care team to see if preventive medicines are safe for you.
Tests and procedures used for colon cancer diagnosis include:
Blood tests. Blood tests aren't used to diagnose colon cancer. But blood tests can give clues about overall health, such as how well the kidneys and liver are working. A blood test might be used to look for a low level of red blood cells. This result might indicate that a colon cancer is causing bleeding.
Colon cancers sometimes make a protein called carcinoembryonic antigen, also called CEA. Blood tests can track the level of CEA over time. The results might show whether the cancer is responding to treatment. After treatment, CEA blood tests might detect if the cancer comes back.
After a colon cancer diagnosis, other tests might be needed to find out the extent of the cancer. This is called the cancer's stage. The health care team considers the cancer's stage when creating a treatment plan.
Staging tests might include imaging scans of the abdomen, pelvis and chest. Imaging tests take pictures of the body. They show the location and the size of the colon cancer. Often, doctors can't be certain of the cancer's stage until after colon cancer surgery.
Colon cancer stages range from 0 to 4. The lowest numbers mean the cancer is all inside the lining of the colon. By stage 4, the cancer is considered advanced and has spread to other areas of the body. When cancer spreads, it's called metastatic cancer.
Colon cancer treatment usually involves surgery to remove the cancer. Your health care team might recommend other treatments, such as radiation therapy and chemotherapy. Your treatment options depend on the cancer's location and its stage. Your health care team also considers your overall health and your preferences when creating a treatment plan.
Treatment for a very small colon cancer might be a minimally invasive approach to surgery, such as:
If the cancer has grown into or through the colon, a surgeon might recommend:
Surgery to create a way for waste to leave the body. Sometimes it's not possible to reconnect the healthy portions of the colon or rectum after colectomy. The surgeon creates an opening in the wall of the abdomen from a portion of what's left of the intestine. This procedure, called an ostomy, allows stool to leave the body by emptying into a bag that fits over the opening.
Sometimes the ostomy is only for a short time to let the colon or rectum heal after surgery. Then it's reversed. Sometimes the ostomy can't be reversed and stays for life.
When it's not possible to remove the cancer with surgery, a surgeon might try to relieve symptoms rather than cure the cancer. This surgery can remove colon blockages and ease symptoms, such as bleeding or pain.
Sometimes the cancer has spread only to the liver or lung in someone who is otherwise healthy. Surgery or other localized treatments might remove the cancer. Chemotherapy might be used before or after this type of procedure. This approach provides a chance to be free of cancer over the long term.
Chemotherapy uses strong medicines to kill cancer cells. Chemotherapy for colon cancer is usually given after surgery if the cancer is large or has spread to the lymph nodes. Chemotherapy can kill cancer cells that might be left after surgery. This helps reduce the risk of the cancer coming back.
Chemotherapy might also be used before surgery to shrink a large cancer so that it's easier to remove.
Chemotherapy also can be used to relieve symptoms of colon cancer that can't be removed with surgery or that has spread to other areas of the body. Sometimes it's used with radiation therapy.
Radiation therapy uses powerful energy beams to kill cancer cells. The energy can come from X-rays, protons or other sources.
Radiation therapy can shrink a large cancer before an operation to make it easier to remove. When surgery isn't an option, radiation therapy might be used to relieve symptoms, such as pain. Some people have radiation and chemotherapy at the same time.
Targeted therapy uses medicines that attack certain chemicals in cancer cells. By blocking these chemicals, targeted treatments can cause cancer cells to die.
Targeted therapy is usually combined with chemotherapy. Targeted therapy is typically used for people with advanced colon cancer.
Immunotherapy is a treatment with medicine that helps the body's immune system kill cancer cells. The immune system fights off diseases by attacking germs and other cells that shouldn't be in the body. Cancer cells survive by hiding from the immune system. Immunotherapy helps the immune system cells find and kill the cancer cells.
Immunotherapy is usually reserved for advanced colon cancer.
Palliative care is a special type of health care that focuses on relieving pain and other symptoms of a serious illness. Palliative care is done by a team of health care professionals. The team can include doctors, nurses and other specially trained professionals. Their goal is to improve the quality of life for people with serious illness and their families.
Palliative care is an extra layer of support during cancer treatment. When palliative care is used with all other appropriate treatments, people with cancer may feel better and live longer.
It can be hard to cope with a cancer diagnosis. In time, people learn to cope in their own ways. Until you find what works for you, you might try to:
Find someone to talk with. Find a good listener who will listen to you talk about your hopes and fears. This may be a friend or family member. Talking to a counselor, medical social worker, clergy member or cancer support group also might be helpful.
Ask your health care team about support groups in your area or contact a cancer organization, such as the National Cancer Institute or the American Cancer Society.
If you have colon cancer, you'll likely be referred to specialists who treat the disease. You might meet with:
Here's some information to help you get ready for your appointment.
Ask a family member or friend to go to your appointment with you to help you remember the information you're told.
Make a list of:
Some basic questions to ask include:
Be prepared to answer some basic questions about your symptoms, such as:
