Colon cancer is a type of cancer that starts in your colon (large intestine) or rectum. Your colon and rectum are the organs that make up the lower portion of your digestive system.

According to the Centers for Disease Control and Prevention (CDC), colon cancer — also known as colorectal cancer — is the third most common type of cancer in the United States when certain common skin cancers are excluded. In fact, the American Cancer Society (ACS) estimates that about 1 in 23 men and 1 in 25 women will develop colorectal cancer during their lifetime.

The symptoms, treatment, and outlook for colon cancer will generally depend on the stage your cancer is in when you’re first diagnosed.

Learn more about colon cancer stages, causes, and risk factors — plus resources to help you find support.

Doctors use staging as a general guideline to figure out how far along the cancer is. It’s important for a doctor to know the stage of the cancer because it helps determine the best treatment plan for you. It’s also a good way to estimate your long-term outlook.

Stage 0 colon cancer is the earliest stage, and stage 4 is the most advanced stage. Here’s how the stages are defined:

  • Stage 0. Also known as carcinoma in situ, in this stage abnormal cells are only in the inner lining of the colon or rectum.
  • Stage 1. The cancer has penetrated the lining, or mucosa, of the colon or rectum and may have grown into the muscle layer. It hasn’t spread to nearby lymph nodes or to other parts of the body.
  • Stage 2. The cancer has spread to the walls of the colon or rectum, or through the walls to nearby tissues, but hasn’t affected the lymph nodes.
  • Stage 3. The cancer has moved to the lymph nodes but not to other parts of the body.
  • Stage 4. The cancer has spread to other distant organs, such as the liver or lungs.

You might not experience colon cancer symptoms at all, especially in the early stages. If you do experience symptoms in stages 0 through 2, they’ll often include:

Many of these symptoms can also be caused by other, less serious, conditions. However, it’s a good idea to see a doctor if you’ve had any of these symptoms for longer than a week or two. You and your doctor can talk about your symptoms and decide if colon cancer screening is appropriate.

Stage 3 or 4 symptoms (late-stage symptoms)

Colon cancer symptoms are more noticeable in stages 3 and 4. In addition to the above symptoms, you might also experience:

If colon cancer spreads to other parts of your body, you may also experience:

Symptoms by stage

Stage 1 symptomsStage 2 symptomsStage 3 symptomsStage 4 symptoms
constipationconstipationexcessive fatiguejaundice
diarrheadiarrheaunexplained weaknessswollen hands and feet
changes in stool color or shapechanges in stool color or shapeunintentional weight lossbreathing difficulties
blood in stoolblood in stoolchanges in stool that last longer than a monthchronic headaches
bleeding from rectumbleeding from rectuma feeling that your bowels won’t completely emptyblurry vision
excessive gasexcessive gasvomitingbone fractures
abdominal crampsabdominal cramps
abdominal painabdominal pain

It might surprise you to learn that there is more than one type of colon cancer. There are different types of cells that turn cancerous and there are cells in different parts of the digestive tract that can lead to colon cancer.

The most common type of colon cancer starts from adenocarcinomas. Adenocarcinomas form within the cells that make mucus in either the colon or rectum. According to the ACS, adenocarcinomas make up most colon cancer cases.

Less commonly, colon cancers are caused by other types of tumors, such as:

  • lymphomas, which can form in lymph nodes or in the colon first
  • carcinoids, which start in hormone-making cells within your intestines
  • sarcomas, which form in soft tissues such as muscles in the colon
  • gastrointestinal stromal tumors, which can start off as benign and then become cancerous (They usually form in the digestive tract, but rarely in the colon.)

Researchers are still studying the causes of colon cancer.

Cancer may be caused by genetic mutations that can either be inherited or acquired. These mutations don’t guarantee you’ll develop colon cancer, but they do increase your chances.

Some mutations may cause abnormal cells to accumulate in the lining of the colon, forming polyps. These are small, benign growths. However, untreated polyps can become cancerous. Removing these growths through surgery can be a preventive measure.

There are some risk factors that can increase your chances of developing colon cancer. Having one of these risk factors doesn’t automatically mean you’ll get colon cancer, but it does make it more likely than if you had no risk factors.

Risk factors you can’t change

Some factors that increase your risk of developing colon cancer can’t be changed. For instance, your age, ethnicity, and family health history can all impact your risk of colon cancer.

Risk factors you can’t control include:

  • being over 50
  • a prior history of colon polyps
  • a prior history of bowel diseases
  • a family history of colorectal cancer
  • having certain genetic syndromes, such as familial adenomatous polyposis (FAP)
  • being of African or Ashkenazi Jewish descent

Risk factors you can avoid

Other risk factors are avoidable. This means you can change them to decrease your risk of developing colon cancer. Avoidable risk factors include:

An early diagnosis of colon cancer gives you the best chance of curing it. Since colon cancer often has no symptoms during the early stages, it is often caught during routine screenings.

The US Preventive Service Task Force (USPSTF) and the ACS now recommend colon cancer screening starting at 45, in light of younger people getting diagnosed with colon cancer.

The American College of Gastroenterology recommends that people start colon cancer screening at 40 years old.

Your doctor will start by getting information about your medical and family history. They’ll also perform a physical exam. They may press on your abdomen or perform a rectal exam to determine whether lumps or polyps are present.

Fecal testing

The ACS recommends yearly fecal testing. Fecal tests are used to detect hidden blood in your stool. There are two main types, the guaiac-based fecal occult blood test (gFOBT) and the fecal immunochemical test (FIT).

Guaiac-based fecal occult blood test (gFOBT)

Guaiac is a plant-based substance used to coat a special card that your stool sample is placed upon. If any blood is present in your stool, the card will change color.

You’ll have to avoid certain foods and medications, such as red meat and nonsteroidal anti-inflammatory drugs (NSAIDs), before this test. They may interfere with your test results.

Fecal immunochemical test (FIT)

The FIT detects hemoglobin, a protein found in the blood. It’s considered more precise than the guaiac-based test.

That’s because the FIT is unlikely to detect bleeding from the upper gastrointestinal tract (a type of bleeding that is rarely caused by colorectal cancer). Additionally, the results of this test aren’t affected by foods and medications.

At-home tests

Because multiple stool samples are needed for these tests, your doctor will likely provide you with test kits to use at home.

You can also buy at-home test kits from companies such as LetsGetChecked and Everlywell.

These kits often require you to send a stool sample off to a lab for evaluation. Your test results should be available online within 5 business days. Afterward, you’ll have the option to consult with a medical care team about your test results.

The Second Generation FIT can also be purchased online, but the stool sample doesn’t have to be sent to a lab. Test results are available within 5 minutes. This test is accurate, FDA-approved, and able to detect additional conditions such as colitis. However, there’s no medical care team to consult with if you have questions about your results.

Blood tests

Your doctor may run blood tests to get a better idea of what’s causing your symptoms. Liver function tests and complete blood counts can rule out other diseases and disorders.

Sigmoidoscopy

Minimally invasive, sigmoidoscopy allows your doctor to examine your sigmoid colon, the last section of your colon, for abnormalities. The procedure, also known as flexible sigmoidoscopy, involves a flexible tube with a light on it.

The USPSTF recommends a flexible sigmoidoscopy every 5 years, or every 10 years along with a yearly FIT test.

The ACS recommends a flexible sigmoidoscopy every 5 years.

Colonoscopy

A colonoscopy involves the use of a long tube with a small camera attached. This procedure allows your doctor to see inside your colon and rectum to check for anything unusual. It’s usually performed after less invasive screening tests indicate that you might have colon cancer.

During a colonoscopy, your doctor can also remove tissue from abnormal areas. These tissue samples can then be sent to a laboratory for analysis.

Out of the existing diagnostic methods, sigmoidoscopies and colonoscopies are the most effective at detecting benign growths that may develop into colon cancer.

The USPSTF and the ACS recommend a colonoscopy every 10 years.

X-ray

Your doctor may order an X-ray using a radioactive contrast solution that contains the chemical element barium.

Your doctor inserts this liquid into your bowels through the use of a barium enema. Once in place, the barium solution coats the lining of the colon. This helps improve the quality of the X-ray images.

CT scan

CT scans provide your doctor with a detailed image of your colon. A CT scan that’s used to diagnose colon cancer is sometimes called a virtual colonoscopy.

Treatment of colon cancer depends on a variety of factors. A doctor will determine the best treatment plan for you based on your overall health and the stage of your colon cancer.

Surgery

In the earliest stages of colon cancer, it’s often possible for your surgeon to remove cancerous polyps through surgery. If the polyp hasn’t attached to the wall of the bowels, you’ll likely have an excellent outlook.

Your surgeon may need to remove a portion of the colon or rectum and the neighboring lymph nodes If your cancer has spread into your bowel walls. Your surgeon might be able to reattach the remaining healthy portion of the colon to the rectum. If this isn’t possible, they may perform a colostomy. This involves creating an opening in the abdominal wall for the removal of waste. A colostomy may be temporary or permanent.

Chemotherapy

Chemotherapy involves the use of drugs to kill cancer cells. For people with colon cancer, chemotherapy commonly takes place after surgery and is used to destroy lingering cancerous cells. Chemotherapy also controls the growth of tumors.

Chemotherapy drugs used to treat colon cancer include:

  • capecitabine (Xeloda)
  • fluorouracil
  • oxaliplatin (Eloxatin)
  • irinotecan (Camptosar)

Chemotherapy often comes with side effects that need to be controlled with additional medication.

Radiation

Radiation uses a powerful beam of energy, similar to that used in X-rays, to target and destroy cancerous cells before and after surgery. Radiation therapy commonly occurs alongside chemotherapy.

Other medications

Targeted therapies and immunotherapies may also be recommended. Drugs that have been approved by the Food and Drug Administration (FDA) to treat colon cancer include:

  • bevacizumab (Avastin)
  • ramucirumab (Cyramza)
  • ziv-aflibercept (Zaltrap)
  • cetuximab (Erbitux)
  • panitumumab (Vectibix)
  • regorafenib (Stivarga)
  • pembrolizumab (Keytruda)
  • nivolumab (Opdivo)
  • ipilimumab (Yervoy)

They can treat metastatic, or late-stage, colon cancer that doesn’t respond to other types of treatment and has spread to other parts of the body.

It can be alarming and stressful to get a serious diagnosis like colon cancer. Fortunately, colon cancer is treatable, especially when detected early. In fact, according to the ACS, colon cancer that’s diagnosed before it has spread past the colon and rectum has a 91 percent 5-year survival rate. Additionally, these survival rates are based on data from 2010 to 2016. New cancer treatments have led to increasingly improved outcomes in more recent years.

However, colon cancer cases have also risen among younger people in recent years. According to the ACS, while colon cancer deaths declined in older adults, deaths in people younger than 50 years old increased between 2008 and 2017.

Colon cancer stage at diagnosisSurvival rate
Stage 0 and Stage 191%
Stage 2 and Stage 372%
Stage 414%
Overall 63%

Certain risk factors for colon cancer, such as family history and age, aren’t preventable.

However, lifestyle factors that may contribute to colon cancer are preventable, and changing them might help lower your overall risk of developing this disease.

You can take steps now to reduce your risk by:

Another preventive measure? Getting a colonoscopy or other cancer screening when you turn 45 years old. The earlier the cancer is detected, the better the outcome.

Surgery is often the first step in treating colon cancer. Your next steps will depend on how you respond to surgery and what further treatments you need.

No matter what happens on your treatment journey, you’ll need support along the way. It’s important to talk to your medical team and loved ones and to feel comfortable reaching out for help. Check out the resources below to start building a support system.

  • The Colorectal Cancer Alliance Helpline (877-422-2030) is a free service that can connect you to resources and peer support.
  • The Colorectal Cancer support group live chatmeets every weekday between 12 pm and 1 pm EST.
  • Blue Hope Nation is a supportive Facebook group for colon cancer patients and famiy members.
  • CancerCare offers a Colorectal Cancer Patient Support Group led by an oncology social worker.
  • Fight Colorectal Cancer offers a resource library for people with colon cancer including videos, podcasts, and more to support you through treatment and beyond.