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What is Colorectal Cancer?

Colorectal [koh-luh-REK-tl] cancer is cancer that originates in the colon or rectum. Cancer happens when cells multiply too fast and don’t die when they should, which can create a mass of cells known as a tumor. In colon cancer, the large intestine, which is part of the lower bowel, develops these malignant [muh-lig-nuh nt] cancer cells that form tumors in the lining of the colon. The colon is a part of the large intestine, making up a 5-foot section of the lower bowel that extracts salt and water from undigested food (stool) and pushes the stool along to the rectum. The colon has four parts;

  • Ascending colon. This is the first section of the colon and contains a pouch where the small intestine deposits any remaining undigested food. 
  • Transverse [trans-VURS] colon. This second section travels back to the other side of the body and together with the ascending colon make up what doctors refer to as the proximal [PROK-suh-muh l] colon.
  • Descending colon. This part of the colon travels downward and together with the sigmoid makes up the part of the colon doctors call the distal colon.
  • Sigmoid [SIG-moid] colon. This “s” shaped part attaches to the rectum and is the last section of the colon.

Colorectal cancer is common in both men and women after the age of 50. There are several different types of colon or rectal cancer, depending on the location and type of tumors.

  • Adenocarcinomas [ah-DEE-no-KAR-sihn-OH-muhs]. Most colorectal cancer (95%) is this type in which cancer cells start in the mucus of the colon and rectum.
  • Carcinoid [KAHR-suh-noid] tumors. This type of colorectal cancer is caused by hormone-making in the colon.
  • Gastrointestinal stromal [gas-troh-in-tes-tuh-nl-STROH-mal] tumors (GISTS). These tumors are caused by specialized cells that attach to the walls of the colon.
  • Lymphomas [lim-FO-muhs]. This type of immune system cancer usually begins in the lymph nodes but can sometimes start in the colon.
  • Sarcomas [sahr-koh-muhs]. This is a type of rare, soft-tissue tumor that affects blood vessels and the muscles and tissue of the colon.


Colorectal cancer often has few symptoms until it reaches the advanced stages, so it’s important that both men and women over the age of 50 have yearly screenings. The symptoms of colon or rectal cancer can include the following:

  • Diarrhea or constipation
  • A feeling that the bowel is still full even after passing stools
  • Blood in the stool
  • Narrow stools
  • Frequent gas or cramps
  • Weight loss
  • Fatigue
  • Nausea or vomiting

When to See a Doctor

If you experience any of the above symptoms, you should consult your doctor, who may order tests to see if you have colorectal cancer. Because it is the third most common type of cancer among men and women, yearly screenings for people over the age of 50 are highly recommended. If you have risk factors, your doctor may suggest a more frequent schedule for screening.


Colorectal cancer is one of the few cancers in which inherited or genetic risk factors are not widely present, but there are some lifestyle factors that can influence whether you are at greater risk for colorectal cancer, such as:

  • Diet. Foods high in fat but low in fiber can lead to increased risk of colon cancer, especially eating broiled, grilled, and fried meats often.
  • Colorectal polyps. If you’ve previously had these benign [bih-NINE] growths or they are common in your family, you may be at higher risk for colon cancer.
  • Ulcerative colitis [UHL-suh-rey-tiv-kuh-ALHY-tis] and Crohn’s disease. These chronic conditions of the digestive system can lead to increased risk of colorectal cancer. 
  • Smoking. As with many types of cancer, smoking increases your risk of developing colon cancer.
  • Age. Colon cancer is more common in both men and women after 50 years of age. 
  • Race. There seems to be an increased risk for colon cancer associated with being of African American or Eastern European Jewish ancestry, but scientists have been unable to determine why.

Diagnosis and Tests

Several tests can be done to determine if you have colorectal cancer. They might include some or all of these:

  • Digital rectal exam
  • Colonoscopy [COL-uhn-AHS-kuh-PEE]
  • Fecal [FEE-kuh l] occult blood test
  • Blood test
  • Barium enema [BAIR-ee-uh m-EN-uh-muh] or x-rays of the intestine
  • Biopsy

Your doctor might order other tests not listed here to help diagnose this kind of cancer.

Your doctor’s diagnosis will usually include which stage of cancer you have. A stage is defined as not only how far the cancer has spread, but to what parts of the body. The stages of colorectal cancer are generally defined here, but there are sub-stages and specifics with each stage that you should discuss in depth with your doctor.

  • Stage 0: This is the earliest stage of cancer where the cells have not grown beyond the inner layer of the intestine.
  • Stage 1: This stage describes growth into the wall of the intestine but has not spread to any lymph [LIMF] nodes or other areas.
  • Stage 2: The outermost layers of the colon are affected by cancer at this stage, but other organs and lymph nodes are not.
  • Stage 3: Tumors have penetrated through the layers of the colon but not reached other organs. Some surrounding lymph nodes are usually affected at this stage. 
  • Stage 4: Tumors have penetrated the colon and cancerous cells have spread to other organs of the body, with or without affecting lymph nodes. The most common organs to be affected at this point are the liver and the lungs. This stage is often referred to as metastasized [muh-TAS-tuh-sahyz-d] cancer.

For a more detailed explanation of the stages and sub-stages of colorectal cancer, consult your doctor or oncologist.


Treatment for colorectal cancer is usually done by a specialist who is part of a treatment team. Often that team includes not only your doctor but a gastroenterologist [GAH-strow-EHN-troh-AHL-ih-JIST], an oncologist [on-CALL-oh-jist], a colorectal surgeon, and a radiation or medical oncologist . They may recommend some of the following measures to address your colon or rectal cancer:

  • Surgery. If the cancer is detected early, this is one of the most effective ways to treat colorectal cancer. 
  • Medicines. This includes not only chemotherapy [KEE-moh-THER-uh-PEE] but also targeted drug therapies and immunotherapy [ih-MYOO-noh-THER-uh-PEE].
  • Radiation. Depending on the stage of your cancer, radiation therapy may be used along with medicines and/or surgery.

The treatment method recommended for your colon cancer will depend on the stage of cancer, whether the colon is blocked or partially blocked, and your general health. In some cases as a result of surgery, a colostomy [kuh-LOS-tuh-mee] will be performed in which a stoma [STOH-muh] is installed that allows your stool to be emptied into an attached bag. This may be temporary or permanent depending on the details of your procedure.

Additional alternative cancer treatments focus on pain management and improving quality of life, but should only be done under the supervision of your treatment team to avoid complications.

How Can Colorectal Cancer Be Prevented?

Because colorectal cancer has several kinds of risk factors, it can be prevented in part by addressing those lifestyle factors that are within your control. Many cancers share the same kinds of risk factors. Here are just a few to focus on to prevent colorectal and in many cases, other types of cancer.

  • Quit smoking. Smoking is a major factor in increased risk of cancer, not just of the lungs, but in other parts of the body.
  • Drink less alcohol. Excessive consumption of alcohol has been linked to a greater risk of cancer.
  • Exercise. A healthy lifestyle that includes daily exercise can lower general cancer risk.
  • Eat a healthy diet. A diet low in fat and high in fiber can reduce your risk of colorectal cancer.

Doctors also advise yearly screenings for colorectal cancer to promote early detection and improve the prognosis of those who are diagnosed with colon cancer.

Colorectal cancer is one of the most common types of cancers to affect both men and women, especially over the age of 50. It involves cancer of the colon and rectum and can be associated with lifestyle risk factors like diets high in fat, smoking, and lack of exercise.