Medically Reviewed by Sabrina Felson, MD on July 31, 2020

Colorectal Cancer: What Is It?


When doctors find this disease early, it’s highly curable. It happens when abnormal cells grow in the lining of the large intestine (also called the colon) or the rectum. It can strike both men and women, and it has the second highest rate of cancer deaths in the U.S.

What Are Polyps?


They're growths on the inside of your intestines. Most of them are harmless, but some can turn into colorectal cancer if not removed early. The two most common types of intestinal polyps are adenomas and hyperplastic polyps. They form when there are problems with the way cells grow and repair in the lining of the colon.

Risk Factors You Can't Control


Some things you just can’t help, such as:

  • Your age -- most people with it are older than 50
  • Polyps or inflammatory bowel disease
  • Family history of colorectal cancer or precancerous colon polyps


Risk Factors You Can Control


Try to avoid these things that can raise your odds of getting the disease:

  • Eating a lot of red or processed meats, or those cooked at high temperatures
  • Obesity (having too much fat around the waist)
  • Not exercising enough
  • Smoking
  • Heavy alcohol use


What Are the Symptoms?


Colorectal cancer doesn’t have early warning signs, so it's important to get checked. Finding it early means it's more curable. As the disease gets worse, you may see blood in your stool or have pain in your belly, bathroom-related troubles like constipation or diarrhea, unexplained weight loss, or fatigue. By the time these symptoms appear, tumors tend to be bigger and harder to treat.

Tests That Find Colorectal Cancer


Screening tests are key to an early diagnosis. The U.S. Preventative Services Task Force and the American Cancer Society both recommend that most people should have a colonoscopy every 10 years once they turn 45. This test uses a tube with a tiny camera to look at the whole colon and rectum. It can help prevent colorectal cancer by finding tumors early. Your doctor will then remove the polyps (as pictured here).

Virtual Colonoscopy


This uses a CT scan to show a 3-D model of your colon. The test can show polyps or other problems without placing a camera inside your body. The main disadvantages are the test can miss small polyps, and if your doctor does find some, you’ll still need a real colonoscopy. Your doctor may suggest a virtual colonoscopy once every 5 years.

Flexible Sigmoidoscopy


Your doctor may recommend this test instead of a colonoscopy. They'll use a slender tube to look inside your rectum and the bottom part of your colon. The tube has a light and a camera, and it shows polyps and cancer. If your doctor says this is the right test for you, you should get one every 5 years.

Fecal Blood Tests


The fecal occult blood test and fecal immunochemical test can show whether you have blood in your stool, which can be a sign of cancer. Depending on the type of test, you give up to three small samples of your stool to the doctor to study. Doctors typically recommend these tests every year. If your samples show signs of blood, you may need a colonoscopy. 

An at-Home Choice: DNA Test


A new test called Cologuard looks for blood or suspicious DNA in your stool sample. The test is very accurate at finding colon cancer, but if it does, you still need to follow up with a colonoscopy. 

Cologuard can’t take the place of that exam. The American Cancer Society recommends getting a stool DNA test every 3 years. 

The Right Diagnosis


If a test shows a possible tumor, the next step is a biopsy. During the colonoscopy, your doctor takes out polyps and gets tissue samples from any parts of the colon that look suspicious. Experts study the tissue under a microscope to see whether or not it is cancerous. Shown here is a color-enhanced, magnified view of colon cancer cells.

The Stages of Colorectal Cancer


Experts "stage" any cancers they find -- a process to see how far the disease has spread. Higher stages mean you have a more serious case of cancer. Tumor size doesn’t always make a difference. Staging also helps your doctor decide what type of treatment you get.

  • Stage 0: Cancer is in the innermost lining of the colon or rectum.
  • Stage I: The disease has grown into the muscle layer of the colon or rectum.
  • Stage II: Cancer has grown into or through the outermost layer of the colon or rectum.
  • Stage III: It has spread to one or more lymph nodes in the area.
  • Stage IV: It has spread to other parts of the body, such as the liver, lungs, or bones.


Survival Rates


The outlook for your recovery depends on the stage of your cancer. You might hear your doctor talk about the “5-year survival rate.” That means the percentage of people who live 5 years or more after they're diagnosed. Stage I has a 5-year survival rate of 87% to 92%. But remember that those stats can't predict what will happen for everyone. Many things can affect your outlook with colorectal cancer, so ask your doctor what those numbers mean for you. 

Can Surgery Help?


Surgery has a very high cure rate in the early stages of colorectal cancer. In all but the last stage, doctors remove the tumors and surrounding tissue. If they are big, your doctor may need to take out an entire piece of your colon or rectum. If the disease affects your liver, lungs, or other organs, surgery probably won’t cure you. But it may help ease your symptoms.

Fighting Advanced Cancer


Colorectal cancer can still sometimes be cured even if it has spread to your lymph nodes (stage III). Treatment typically involves surgery and chemotherapy. Radiation therapy (shown here) is an option in some cases. If the disease comes back or spreads to other organs, it will probably be harder to cure. But radiation and chemotherapy may still ease your symptoms and help you live longer.

Will Chemo Make Me Feel Bad?


Newer chemotherapy drugs are less likely to make you sick. There are also medicines that can help you control your nausea.

Radiofrequency Ablation (RFA)


This treatment uses intense heat to burn away tumors. Guided by a CT scan, a doctor inserts a needle-like device into a tumor and the surrounding area. The procedure can destroy some tumors that can’t be surgically removed, like in the liver. Chemotherapy can work with RFA.

Prevent Colorectal Cancer With Healthy Habits


You can take steps to dramatically lower your odds of getting the disease. Eat a nutritious diet, get enough exercise, and control your body fat. Those habits prevent many cases of colorectal cancers. 

The American Cancer Society recommends a diet heavy on fruits and vegetables, light on processed and red meat, and with whole grains instead of refined grains. That will help you keep a healthy weight.

Prevent Cancer With Exercise


Adults who stay active seem to have a powerful weapon against colorectal cancer. In one study, the most active people were 24% less likely to have the disease than the least active. It didn't matter whether what they did was work or play. 

The American Cancer Society recommends getting 150 minutes per week of moderate exercise, like brisk walking, or 75 minutes per week of vigorous exercise, like jogging. Try to spread your activity throughout the week.

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American Cancer Society: "Colorectal Cancer Risk Factors," "Colorectal Cancer Prevention and Early Detection," "Survival Rates for Colorectal Cancer by Stage."
Colon Cancer Alliance: "Fecal Immunochemical Test."
Exact Sciences Cologuard: "How Can I Get Screened With Cologuard?"
Harvard Health Publications: "Fecal Occult Blood Test."
National Cancer Institute: "Colorectal Cancer."
National Institute of Diabetes and Digestive and Kidney Diseases: "Flexible Sigmoidoscopy."
Levin, B. Gastroenterology, 2008.