Colon Cancer: Overview

Your guide to diagnosing, treating, and living with colon cancer, with the latest science-based advice from many of the country's leading medical experts.

Do I Need Screening?

There are several easy steps you can take to decrease your risk of developing colorectal cancer. One of the best ways to do that is by getting screened.


Dr. Heather Yeo, on why it’s important for everyone — even those without a family history of colon cancer — to get screened

When it comes to colon cancer prevention, screening is extremely important. Most colon cancers can actually be prevented if people are regularly screened. In fact, the incidence of colon cancer in the United States has been going down over the past two decades, and much of that reduction is thought to be due to screening.

If you're at average risk, meaning you don't have risk factors like smoking or a family history, the American Cancer Society advises getting regular colonoscopies once you turn 45. Colonoscopy is a test that uses a long, thin tube attached to a camera, which lets your doctor check for polyps throughout your whole colon and rectum. You'll get one colonoscopy that will serve as a baseline, and, if your doctor doesn't find any polyps, you'll have another one in 10 years.


Colorectal cancer surgeon, Dr. Zuri Murrell, describes how doctors find and remove polyps during a colonoscopy

You may need to have more frequent colonoscopies if your doctor finds a polyp. Depending on the size and number of polyps, you may need a repeat colonoscopy within three to five years, and maybe more often, based on your individual risks.

For how long should you continue to get screened? While most major health organizations don't put an upper age limit on colonoscopy screening, government guidelines suggest that if you're 76 or older, you should talk to your doctor about whether you need further screening.

Colonoscopy isn't the only colon cancer screening test. There are other options, including stool tests that detect blood or DNA, and flexible sigmoidoscopy, which checks only the lower third of your colon. Ask your doctor whether any of these tests would be good substitutes or additions to colonoscopy, based on your risks and/or personal preferences.

The advantage to colonoscopy is that your doctor can remove any polyps found during the test. Many colon cancers can be caught on colonoscopy before they develop, or when the polyps are small enough to be removed without surgery.

What Are the Symptoms of Colon Cancer?

The sneaky thing about colorectal polyps and colorectal cancer, say SurvivorNet’s medical experts, is that they don't necessarily lead to symptoms, which is why screening is necessary for everyone over age 50 (and sometimes earlier), even people who feel well.


Gastrointestinal oncologist, Dr. Paul Oberstein, describes the most common symptoms of colon cancer

When symptoms do appear, one of the most common is a change in bowel habits. This ranges from constipation or diarrhea to differences in the size or shape of bowel movements. A change in stool color, particularly black or tarry stools, can indicate bleeding from a tumor that lies deep in the colon.

Other symptoms can be harder to pinpoint as cancer, such as abdominal pain and unintentional weight loss. Finally, some tumors bleed a small amount over a long period of time, resulting in anemia (a low red blood cell count) that is picked up on a blood test.

A few other possible symptoms of colon cancer are:

  • Cramps
  • Gas
  • Weakness
  • Tiredness

Any symptoms that are new or unusual for you, or that persist for more than a week or two, warrant a call to your doctor.

Getting a Diagnosis

Your doctor can diagnose you after analyzing the results of your colonoscopy and, if necessary, removing a small sample of tissue from your colon to test for cancer (called a biopsy). Blood tests might be used to get a read on your overall health, as well as to look for a protein that colon cancers sometimes produce (called carcinoembryonic antigen, or CEA).

A colon cancer diagnosis can be an anxiety-provoking experience, but there are a few basic things you can do to help manage the process:

  • Have someone come with you to the doctor. It is important to bring a close friend or family member, not only to support you, but also to help you understand and digest all of the information you'll receive.
  • Take notes. Writing down what you hear can help you focus and create a record of the information so you can refer to it later on.
  • Don't be afraid to get a second opinion. Your doctor won't be offended if you get a second opinion. It is extremely important to go through the process with a doctor you trust.


Dr. Heather Yeo offers advice on managing the anxiety surrounding a colon cancer diagnosis

After your blood tests come back, your doctor will stage your cancer. Staging takes into account the depth of the tumor in the colon, and whether the cancer has spread to the lymph nodes or to other organs, such as the liver or lungs.

A preliminary staging workup is done after diagnosis with imaging studies, such as a computed tomography (CT) scan, which can show whether the cancer has spread. If you have had surgery to remove your cancer, a pathologist will look at it under a microscope to determine your stage.

  • Stage I cancers are those in which the tumor has only penetrated the superficial layers of the colon, and haven't gotten into the deeper layers
  • Stage II cancers involve the deeper layers of the colon wall
  • Stage III cancers have spread to the lymph nodes around the colon
  • Stage IV cancers have spread to other organs, such as the liver, lungs, or peritoneal cavity (the space in your abdomen that holds your intestines, stomach, and liver)

Which Treatments are Best for You?

Your doctor has many ways to treat colon cancer, including:


Surgery is the main treatment for most early-stage colon cancers, according to the doctors SurvivorNet spoke with. The surgeon will remove the part of the colon or rectum where there is cancer, along with a small area of healthy tissue around it. Taking out as much of the cancer as possible is important for improving your outcome.

The surgery may be performed through small incisions (laparoscopy), or through a larger incision. Some people may need to wear a special bag (ostomy) to collect wastes after surgery.


How does laparoscopic surgery compare to open surgery? Dr. Zuri Murrell explains.

Radiation Therapy

This treatment aims high-energy x-rays at the cancer to destroy the abnormal cells. The radiation can come from a machine outside your body, or be placed directly inside your body. Sometimes people get radiation before surgery, to shrink the tumor and make it easier for the surgeon to remove. This is called neoadjuvant radiation.


This treatment uses strong medicine to stop cancer cells from dividing, no matter where they are in your body. You may get a combination of chemotherapy drugs as your first treatment. Chemotherapy has been very well studied for colorectal cancer, and it is known to improve survival.

The most common therapy is a combination of chemo drugs called FOLFOX:

  • FOL = leucovorin calcium (folinic acid)
  • F = fluorouracil
  • OX = oxaliplatin

Your doctor may add medications like irinotecan (FOLFIRI) or cetuximab, depending on how well your tumor shrinks with treatment and other specifics about your particular cancer. For FOLFOX, the medications are given through the vein and require regular doctor visits.

To determine exactly which chemotherapy regimen you get, your doctor will consider your age and how well you might tolerate the side effects of chemotherapy. Gene mutations (for example, BRAF and KRAS) and the location of the primary colon tumor also factor into the decision.

You can also get chemotherapy before colon cancer surgery, which is called neoadjuvant chemotherapy. Getting chemo first helps to shrink the tumor, which can make both the surgery and recovery easier, according to SurvivorNet’s experts. Chemo is also a treatment for cancer that returns after therapy.


Dr. Paul Oberstein explains why it sometimes makes sense to give chemotherapy before surgery.

Targeted Therapy

This treatment targets substances like proteins or genes that the cancer needs to grow. This makes targeted therapy more precise than chemotherapy, and less likely to damage healthy cells. One example of targeted therapy is bevacizumab (Avastin), which stops the growth of new blood vessels that feed tumors. Another group of targeted therapies are called epidermal growth factor receptor (EGFR) inhibitors, which block the cancer from growing.


This treatment makes your own immune system a more efficient cancer fighter. A group of drugs called checkpoint inhibitors, which includes pembrolizumab (Keytruda) and nivolumab (Opdivo), work by preventing cancer cells from hiding from your immune system. Checkpoint inhibitors may extend the amount of time before the cancer spreads.

Treating Colon Cancer By Stage

While early stage colorectal cancer has good survival rates, in the later stages treatment can get a little more complex. It’s important for you and your doctor to understand as much as possible about your cancer, so that you can make the right decisions about your care.

Generally, surgery is recommended for anyone with stage I, II, or III colon cancer, though people with stage II and III cancers may need both surgery and chemotherapy. Even if surgery is successful at removing your cancer, there are always risks. That can mean anything from an infection that is treated with antibiotics, to a problem with the surgery itself that requires another procedure to correct.

The risk of complications is higher for older people and those who have other medical problems (like heart and lung disease). In these situations, your surgeon can help you decide whether surgery is the right option for you, and what other choices you might have to prolong your life while also maintaining your quality of life.

Late-Stage Colon Cancer Treatment

Metastatic colon cancer is when the tumor has spread outside the colon. The advanced stages of colorectal cancer are not always curable. But because there are so many treatment options available, the disease can often be managed, even in its late stages, according to SurvivorNet’s experts. Thankfully, there have been major advancements in colon cancer research in recent years that have led to new and better treatments.


Dr. Paul Oberstein, on which treatments doctors use to turn stage 4 colon cancer into a chronic but manageable disease

Stage 4 colon cancer is often managed with chemotherapy alone or, in select cases, a combination of chemotherapy and surgery. Sometimes it is not possible to surgically remove all of the tumors. The primary goal of treatment then is to manage the cancer; in other words, to prevent it from growing, spreading, and causing symptoms. Radiation is also often used to help prevent symptoms or treat any pain that may rise from the tumor traveling to other parts of the body.

It is important to continue to follow up with your doctor after treatment, even if your cancer is considered cured, to make sure that it doesn't come back.


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