Colon Cancer



Colon cancer is the growth of cancer in the large intestine. The large intestine, or colon, absorbs water and nutrients from foods. After, the colon passes the solid waste to the rectum for storage, before it is eliminated from the body.

Colon Cancer
Copyright © Nucleus Medical Media, Inc.


Cancer occurs when cells in the body divide without control or order. Eventually these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths. These growths can invade nearby tissues and spread to other parts of the body. It is not clear exactly what causes these problems in the cells, but it is probably a combination of genetics and environment.

Risk Factors

Being over 50 years old increases your chance of colon cancer. Other factors that may increase your chances of colon cancer:

  • Hereditary conditions, such as familial adenomatous polyposis
  • Personal history of colon or rectal cancer, or polyps
  • Family history of colon or rectal cancer, especially a parent, sibling, or child
  • Ethnicity—African-Americans carry the highest risk of developing and dying from colon and rectal cancers
  • History of ulcerative colitis or Crohn disease
  • Obesity
  • Smoking
  • Diets high in meat, and low in fruits, vegetables, and whole grains
  • Alcohol use disorder
  • Physical inactivity



In most cases, there are no symptoms with colon cancer. When symptoms do appear, they may include:

  • A change in bowel habits
  • Blood in the stool that is either bright red or black and tarry
  • Stools that are narrower than usual
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • General abdominal discomfort, such as frequent gas pains, bloating, fullness, and/or cramps
  • Unexplained weight loss
  • Constant feeling of fatigue or tiredness


You will be asked about your symptoms and medical history. A physical exam will be done. The doctor will check the rectum for lumps or abnormal areas, and recommend different tests in order to identify tumors and confirm diagnosis.

Tests used to identify potential colon cancers include:

  • Fecal occult blood test
  • Colonoscopy
  • Sigmoidoscopy
  • Barium enema
  • CT colonography

Additional tests may confirm the presence of colon cancer, determine what stage the cancer is in, and/or determine if the cancer has spread:

  • Biopsy
  • Polypectomy
  • CT scan
  • PET scan
  • Transrectal ultrasound
  • Blood tests to look for anemia and tumor markers in the blood

The physical exam, combined with all of your test results, will help to determine the type and stage of cancer you have. Staging is used to guide your treatment plan. Like other cancers, colon cancer is staged from I-IV. Stage I is a very localized cancer, while stage IV indicates a spread to other parts of the body



Treatment for colon cancer depends on how early it is detected, and the stage or location of the tumor.

Talk with your doctor about the best treatment plan for you. Treatment may include one or more of the following options:


Surgery is the main treatment for colon cancer. There are several options for surgery depending on the location of the cancer and how much it has spread:

  • Polypectomy and local excision—Early stage removal of the cancer.
  • Partial colectomy—Removal of the cancer with a margin of surrounding healthy tissue and lymph nodes. The healthy ends of the colon are reconnected.
  • Laparoscopic-assisted colectomy—Removal of the cancer with a margin of surrounding healthy tissue and lymph nodes through small incisions in the abdomen.
  • Total colectomy—Removal of the entire colon. The last part of the small intestine, called the ileum, is then connected to the rectum.

Some surgeries may require temporary or permanent colostomies. A colostomy is a surgical opening through the wall of the abdomen into the colon. This is used as a path for waste material to leave the body. After a colostomy, you will wear a special bag to collect bodily waste.

Radiation Therapy

Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. It is directed at the site of the tumor from a source outside the body. This therapy is aimed at the immediate area of the cancer.


Chemotherapy uses drugs to kill cancer cells. It may be given in many forms, including pill, injection, and catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells. They can also kill some healthy cells. This therapy is systemic, meaning it affects your entire body.


Targeted Therapy

Targeted therapy uses medications to target and kill cancer cells, while sparing healthy tissue. They are currently used to treat advanced cancers. Targeted therapy is less harmful to healthy tissue, which reduces side effects. It may be used alone or in combination with chemotherapy.

Other Medications

Some medications can be used as part of a treatment plan. Other medications may help to either prevent or reduce side effects of treatments, or to manage certain side effects once they occur. These include:

  • Corticosteroids
  • Blood stem cell support medications
  • Antiemetics to control nausea
  • Nonsteroidal anti-inflammatory medications
  • Opioids to control pain

Tell your doctor when you notice a new symptom, and ask if any of these medications are appropriate for you.



The causes of most cancers are not known. However, it is possible to prevent many colon and rectal cancers by finding and removing polyps that could become cancerous. Beginning at age 50, both men and women with average risk should follow one of the following screening options:

  • Colonoscopy every 10 years
  • Flexible sigmoidoscopy every 5 years
  • CT colonography every 5 years
  • Double-contrast barium enema every 5 years
  • MR colonography every 5 years
  • Stool DNA test every 3 years
  • Annual fecal occult blood test (FOBT)
  • Annual fecal immunochemical test (FIT)

People with any of the following risk factors should begin colon and rectal cancer screening earlier and/or undergo screening more often:

  • African American or Native Americans
  • Strong family history of colon or rectal cancer, or polyps
  • Family history of hereditary colon or rectal cancer syndromes
  • History of colon or rectal cancer, or adenomatous polyps
  • History of chronic inflammatory bowel disease

Be sure to discuss colon cancer screening with your doctor to see how and when you should be screened.

Lifestyle Changes

There are lifestyle changes that may reduce your risk of colon cancer, such as:

  • Not smoking
  • Eating a healthful diet high in fruits, vegetables, and whole grains, and low in red meat
  • Being physically active by exercising at least 30 minutes a day on most days of the week
  • Drinking alcohol in moderation—maximum of 2 drinks per day for men and 1 drink per day for women
  • Maintaining a healthy weight

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

a (Cancer of the Colon)


American Cancer Society 

National Cancer Institute 


Canadian Cancer Society 

Colorectal Cancer Canada 


Colorectal cancer. American Cancer Society website. Available at: Accessed October 9, 2017.

Colorectal cancer. EBSCO DynaMed Plus website. Available at: . Updated August 7, 2017. Accessed October 9, 2017.

Colorectal cancer screening. EBSCO DynaMed Plus website. Available at: . Updated August 24, 2017. Accessed October 9, 2017.

General information about colon cancer. National Cancer Institute website. Available at: Updated February 27, 2017. Accessed October 9, 2017.

Kushi LH, Doyle C, McCullough M, et al. American Cancer Society Guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with healthy food choices and physical activity. CA: Cancer J Clin. 2012;62(1):30-67.

Rex DK, Johnson DA, Anderson JC, et al. American College of Gastroenterology guidelines for colorectal cancer screening 2009. Am J Gastroenterol. 2009;104(3):739-750.

11/19/2010 DynaMed Plus Systematic Literature Surveillance. : Kirkegaard H, Johnsen NF, Christensen J, Frederiksen K, Overvad K, Tjønneland A. Association of adherence to lifestyle recommendations and risk of colorectal cancer: a prospective Danish cohort study. BMJ. 2010;341:c5504.

12/9/2011 DynaMed Plus Systematic Literature Surveillance. : Aune D, Chan DS, Lau R, et al. Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies. BMJ. 2011;343:d6617.

4/8/2014 DynaMed Plus Systematic Literature Surveillance. : Yee J, Kim DH, et al. Colorectal cancer screening. American College of Radiology (ACR) Appropriateness Criteria. Available at: Updated 2013.