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If You Have Colon or Rectal Cancer

What is colon or rectal cancer?

Cancer that starts in the colon or rectum is often called colorectal cancer. It might also be called colon cancer or rectal cancer. It starts when cells in the colon or rectum grow out of control and crowd out normal cells.

Cancer cells can spread to other parts of the body. Cancer cells from the colon or rectum can sometimes travel to the liver and grow there. When cancer cells do this, it’s called metastasis. The cancer cells in the new place look just like the ones that started growing in the colon or rectum.

Cancer is always named for the place where it starts. So when colorectal cancer spreads to the liver (or any other place), it’s still called colorectal cancer. It’s not called liver cancer unless it starts from cells in the liver.

color illustration of the digestive system which shows the location of the esophagus, stomach, pancreas, rectum, colon, small intestine, gallbladder and liver

Ask your doctor to show you on this picture where your cancer is found.

The colon and rectum

Colon cancer starts in the colon, and rectal cancer starts in the rectum. These organs are both part of the digestive system. This is where food is broken down to make energy and where the body gets rid of solid waste (poop or stool). On the picture above you can see where the colon and rectum are inside the body.

In most cases, colon and rectal cancers grow slowly over many years. Most of those cancers start as a growth called a polyp. Taking out a polyp early may keep it from turning into cancer.

Are there different kinds of colon and rectal cancers?

There are a few types of colon and rectal cancers. Your doctor can tell you more about the kind you have.

The most common kind is called adenocarcinoma. This type of cancer starts in the cells that make mucus to cover the inside of the colon and rectum.

Questions to ask the doctor

  • What kind of colon or rectal cancer do I have?
  • Where exactly is my cancer located?
  • Do I need more tests to either confirm diagnosis or to guide treatment?
  • What will happen next?

How does the doctor know I have colorectal cancer?

Sometimes colon or rectal cancer is found before it causes symptoms. This can happen with screening tests like a colonoscopy. Sometimes, these tests can even prevent colorectal cancer by finding polyps before they become cancer.

If you are having signs or symptoms of colorectal cancer, such as changes in your poop, bleeding, or belly pain, the doctor will ask you questions about your health and do a physical and rectal exam.

If signs are pointing to cancer, more tests will be done. Here are some of the tests you may need:

Colonoscopy: A colonoscopy is a test where a thin tube with a light on the end (called a colonoscope) is put through the anus, into the rectum and colon to look closely at the inside. If any abnormal lump (mass) or polyp is found, a piece of it can be taken (a biopsy) and checked in the lab for cancer cells.

CT or CAT scan: A CT scan is like an x-ray, but it takes more detailed pictures of your insides. CT scans can also be used to help doctors do a biopsy and can show if the cancer has spread.

Ultrasound: For this test, a small wand is moved around on your skin. It gives off sound waves and picks up the echoes as they bounce off tissues. The echoes are made into a picture on a computer screen. It’s used to help find cancer and see if it has spread.

MRI scan: This test uses radio waves and strong magnets instead of x-rays to make detailed pictures. MRI scans are helpful for looking at the liver, brain, and spinal cord.

Chest x-rays: X-rays may be done to see if the cancer has spread to your lungs.

Blood tests: Certain blood tests can tell the doctor more about your overall health.

PET scan: A PET scan uses a kind of sugar that can be seen inside your body with a special camera. If there is cancer, this sugar shows up as “hot spots” where the cancer is found. These scans can also help show if the cancer has spread.

Biopsy: During a biopsy, the doctor takes out a small piece of tissue where the cancer seems to be. The tissue is checked for cancer cells. This is the best way to know if you have cancer.

Gene and protein tests: The cancer cells in the biopsy tissue might be tested for genes or proteins such as RAS, BRAF, MMR and MSI. Knowing which genes or proteins your cancer has can help the doctor decide if treatments like targeted therapy or immunotherapy might help.

Questions to ask the doctor

  • What tests will I need to have?
  • Who will do these tests?
  • Where will they be done?
  • Who can explain the tests to me?
  • How and when will I get the results?
  • Who will explain the results to me?
  • What do I need to do next?

How serious is my cancer?

If you have colon or rectal cancer, the doctor will want to find out how far it has spread. This is called staging. Your doctor will want to find out the stage of your cancer to help decide what type of treatment is best for you.

The stage describes the growth or spread of the cancer through the layers of the wall of the colon or rectum. It also tells if the cancer has spread to nearby organs or to organs farther away.

Your cancer can be stage 0, 1, 2, 3, or 4. The lower the number, the less the cancer has spread. A higher number, like stage 4, means a more serious cancer that has spread far from the colon or rectum. Be sure to ask the doctor about your cancer stage and what it means for you.

Questions to ask the doctor

  • Do you know the stage of the cancer?
  • If not, how and when will you find out the stage of the cancer?
  • Would you explain to me what the stage means in my case?
  • What will happen next?

What kind of treatment will I need?

There are many ways to treat colon and rectal cancers:

  • Surgery and radiation therapy are used to treat a a specific area of the body. They do not affect the rest of the body.
  • Drugs such as chemotherapy, targeted therapy, and immunotherapy go through the whole body. They can reach cancer cells almost anywhere in the body.

Two or more types of treatment may be used at the same time, or they may be given one after the other. The treatment plan that’s best for you will depend on:

  • The stage of the cancer
  • The chance that a type of treatment will cure the cancer or help in some way
  • Your age
  • Other health problems you have
  • Your feelings about the treatment and the side effects that may come with it
  • The specific genes or proteins your cancer might have

Surgery for colon cancer

Most people with colon cancer have some type of surgery. The cancer, a small part of normal colon on either side of the cancer, and nearby lymph nodes are often removed. The 2 ends of the colon are then put back together.

For most colon cancers, an opening on the belly to get rid of body waste (poop) is not needed, but sometimes one is used for a short time. This opening is called a colostomy. If you need a colostomy for a short time, your doctor can tell you more about how to take care of it and when it can come out.

Surgery for rectal cancer

Most people with rectal cancer need surgery. Radiation and chemo might be given before surgery. Sometimes the cancer can be removed through the anus, without cutting through the skin. This might be done to remove some early-stage cancers that are small and close to the anus.

If the rectal cancer is more advanced and close to the anus, surgery will be done to take out the cancer and make an opening on your belly to get rid of body waste (poop). This is called a colostomy. You will need it for the rest of your life.

If the rectal cancer has spread into nearby organs, more surgery is needed. The doctor may take out the rectum and nearby organs, like the bladder, prostate, or uterus, if the cancer has spread to those organs. You will need a colostomy after that surgery. If the bladder is removed, an opening to collect urine or pee (called a urostomy) is needed, too.

If you have a colostomy or a urostomy, you will need to learn how to take care of it. Nurses with special training will see you before and after surgery to teach you what to do.

Ask your doctor what type of surgery you will need. Ask what your body will look like and how it will work after surgery.

Side effects of surgery

Any type of surgery can have risks and side effects. Ask the doctor what you can expect. If you have problems, let your doctors know..

Radiation treatment

Radiation uses high-energy rays (like x-rays) to kill cancer cells. After surgery, radiation can kill small spots of cancer that may not be seen during surgery. If the size or place of the cancer makes surgery hard to do, radiation may be used before the surgery to shrink the tumor so it's easier to take it out. In both cases, radiation helps keep the cancer from coming back in the place where it started. Radiation can also be used to lessen some problems caused by the cancer, like pain.

There are 2 main ways radiation can be given.

  • It can be aimed at the colon or rectum from a machine outside the body. This is called external beam radiation. This kind is used most often for colon or rectum cancer. Getting this treatment is a little like getting an x-ray, but the radiation is stronger.
  • Brachytherapy is another type of radiation. For this treatment, the doctor uses an endoscope (a long, flexible tube) to put small radioactive pieces called seeds very close to the rectal cancer. The seeds are taken out when treatment is done.

Sometimes, both types of radiation might be used.

Side effects of radiation treatments

If your doctor suggests radiation treatment, ask about what side effects you might have. The most common side effects of radiation are:

  • Skin changes where the radiation is given
  • Feeling sick to your stomach
  • Diarrhea, pain when pooping, or blood in the poop
  • Having to pee a lot, burning when you pee, or blood in the pee
  • Feeling very tired (fatigue)

Many side effects can be treated, and most get better after treatment ends. Some might last longer than others. Talk to your cancer care team about what you can expect during and after treatment.


Chemo is the short word for chemotherapy – chemical drugs that attack cancer cells. The drugs may be given through a needle into a vein or taken as pills. The drugs go into the blood and are carried through the body.

Chemo is given in cycles. Each cycle of treatment  includes a break. This break lets the body recover from side effects before the next cycle starts. Most of the time, 2 or more chemo drugs are given. Treatment often lasts for many months.

Chemo after surgery can help some people live longer. This is called adjuvant chemotherapy.  It is given to decrease the risk of the cancer coming back.

Many times chemo is given along with radiation. This is called chemoradiation.

Side effects of chemo

Chemo can make you feel very tired, sick to your stomach, and cause your hair to fall out. But these problems usually go away after treatment ends.

There are ways to treat most chemo side effects. If you have side effects, talk to your cancer care team so they can help.

Targeted therapy

Targeted therapy drugs may be used for certain types of colon or rectum cancer. These drugs affect mainly cancer cells and not normal cells in the body. They may work even if other treatment doesn’t. These drugs have different side effects than chemo.

Side effects of targeted therapy

Side effects of targeted therapy depend on which drug is used. These drugs might cause high blood pressure, low blood counts, heart problems, and liver problems.

There are usually ways to treat most of the side effects caused by targeted drugs. If you have side effects, talk to your cancer care team so they can help.


Immunotherapy is treatment that either boosts your body's immune response or changes how the immune system works to find and attack the colon or rectal cancer cells. These drugs are given into a vein.

Side effects of immunotherapy

Immunotherapy can cause different side effects depending on which drug is used. These drugs may make you feel tired or cause a rash. Most side effects go away after treatment ends. Immunotherapy can also cause more serious problems in other organs, such as the liver, intestines, and thyroid glands.

There are ways to treat most of the side effects caused by immunotherapy. If you have side effects, talk to your cancer care team so they can help.

Colostomy or ileostomy

As part of their colon or rectum cancer treatment, some people need a short-term or long-term colostomy or ileostomy after surgery. A colostomy is when the colon is cut above the cancer and attached to an opening in the skin of the belly to allow body waste (poop) to come out. Sometimes the end of the small intestine, instead of the colon, is connected to an opening in the skin. This is called an ileostomy. Either way, a bag sticks to the skin around the opening to hold the waste. Nurses who are trained on using an ostomy will meet with you to help you understand how it works and how to take care of it.

Clinical trials

Clinical trials are research studies that test new drugs or other treatments in people. They compare standard treatments with others that may be better. Clinical trials are the best way for doctors to find better ways to treat cancer. If your doctor can find one that’s studying the kind of cancer you have, it’s up to you if you want to take part. And if you do sign up for a clinical trial, you can always stop at any time.

If you’d like to learn more about clinical trials that might be right for you, start by asking your doctor if your clinic or hospital offers clinical trials. See Clinical Trials to learn more.

What about other treatments that I hear about?

When you have cancer, you might hear about other ways to treat the cancer or treat your symptoms. These may not always be standard medical treatments. These treatments may include vitamins, herbs, diets, and other things. You may wonder if these treatments are safe and whether they could help you.

Some of these treatments are known to help, but many have not been tested. Some have been shown not to help. A few have even been found to be harmful. Talk to your doctor about anything you’re thinking about using, whether it’s a vitamin, a diet, or anything else.

Questions to ask the doctor

  • What treatment do you think is best for me?
  • What’s the goal of this treatment? Do you think it could cure the cancer?
  • Will treatment include surgery? If so, who will do the surgery?
  • What will the surgery be like?
  • Will I have a colostomy? For how long?
  • Will I have an ileostomy?
  • Will I need other types of treatment, too?
  • What side effects could I have from those treatments?
  • What can I do about side effects that I might have?
  • Is there a clinical trial that might be right for me?
  • What about vitamins or diets that friends tell me about? How will I know if they are safe?
  • How soon do I need to start treatment?
  • What should I do to be ready for treatment?
  • Is there anything I can do to help the treatment work better?

What will happen after treatment?

You’ll be glad when treatment is over. But it’s hard not to worry about cancer coming back. Even when cancer never comes back, people still worry about it. For years after treatment ends, you will see your cancer doctor. Be sure to go to all of these follow-up visits. You will have exams, blood tests, and maybe other tests, like a colonoscopy or imaging tests, to see if the cancer has come back.

At first, your visits may be every 3 to 6 months. Then, the longer you’re cancer-free, the less often the visits are needed.

Having cancer and dealing with treatment can be hard, but it can also be a time to look at your life in new ways. You might be thinking about how to improve your health. Call the American Cancer Society at 1-800-227-2345 or talk to your cancer care team to find out what you can do to feel better.

You can’t change the fact that you have or had cancer. What you can change is how you live the rest of your life – making healthy choices and feeling as well as you can.

For connecting and sharing during a cancer journey

Anyone with cancer, their caregivers, families, and friends, can benefit from help and support. The American Cancer Society offers the Cancer Survivors Network (CSN), a safe place to connect with others who share similar interests and experiences. We also partner with CaringBridge, a free online tool that helps people dealing with illnesses like cancer stay in touch with their friends, family members, and support network by creating their own personal page where they share their journey and health updates.   

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

Biopsy (BY-op-see): Taking out a small piece of tissue to see if there are cancer cells in it.

Colonoscopy (KO-lun-AH-skuh-pee): A test that allows a doctor to look at the inside of the colon.

Colostomy (kuh-LAHS-tuh-me): An opening made on the belly to get rid of solid body waste (poop).

Gastroenterologist (GAS-tro-EN-ter-AHL-uh-jist): A doctor who treats diseases of the digestive or gastrointestinal (GAS-tro-in-TEST-uh-nul) tract. Also called a GI doctor.

Polyp (PAH-lip): A growth found in places like the colon and rectum.

Lymph nodes (limf nodes): Small, bean-shaped sacs of immune cells found all over the body and connected by lymph vessels; also called lymph glands.

Metastasis (meh-TAS-tuh-sis): Cancer cells that have spread from where they started to other places in the body.

Monoclonal antibody (MA-nuh-KLO-nuhl AN-tih-BAH-dee): A man-made version of an immune system protein that’s made to lock onto cancer cells.

Obstruction (ob-STRUK-shun): A blockage that keeps fluid from flowing like it should. 

Urostomy (yur-AHS-tuh-me): An opening on the belly to allow urine (pee) to pass out of the body.

We have a lot more information for you. You can find it online at Or, you can call our toll-free number at 1-800-227-2345 to talk to one of our cancer information specialists.

Last Revised: January 29, 2024

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