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Colorectal cancer

Colorectal cancer; Cancer - colon; Rectal cancer; Cancer - rectum; Adenocarcinoma - colon; Colon - adenocarcinoma; Colon carcinoma; Colon cancer

Colorectal cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon). It is also sometimes simply called colon cancer.

In the United States, colorectal cancer is one of the leading causes of deaths due to cancer. Early diagnosis can often lead to a complete cure.


Barium enema
Digestive system
Rectal cancer - X-ray
Sigmoid colon cancer - X-ray
Spleen metastasis - CT scan
Structure of the colon
Stages of cancer
Colon culture
Large intestine (colon)


Colon cancer - Series
Colostomy - Series
Large bowel resection - Series


Nearly all colorectal cancers begin as noncancerous (benign) lumps (polyps) in the lining of the colon and rectum. These can slowly develop into cancer. 

You have a higher risk for colorectal cancer if you:

Some inherited diseases also increase the risk of developing colorectal cancer. One of the most common is called Lynch syndrome.


Many cases of colon cancer have no symptoms. If there are symptoms, the following may indicate colon cancer:

Exams and Tests

Through screening tests, colon cancer can be detected before symptoms develop. This is when the cancer is most curable. Abnormal stool screening tests should be followed up with a colonoscopy, which can see the entire colon.

Your health care provider will perform a physical exam and press on your belly area. The physical exam rarely shows any problems, although your provider may feel a lump (mass) in the abdomen. A rectal exam may reveal a mass in people with rectal cancer, but not colon cancer.

Blood tests may be done for those diagnosed with colorectal cancer, including:

If you are diagnosed with colorectal cancer, more tests will be done to see if the cancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, or chest may be used to stage the cancer. Sometimes, PET scans are also used.

Stages of colorectal cancer are:

Blood tests to detect tumor markers, such as carcinoembryonic antigen (CEA) may help your provider monitor your progress during and after treatment.


Treatment depends on many things, including the stage of the cancer. Treatments may include:


Stage 0 colon cancer may be treated by removing the tumor using endoscopic surgery (colonoscopy). For stages I, II, and III cancer, more extensive surgery is needed to remove all or part of the colon and rectum that is cancerous. This surgery is called colon resection (colectomy).


Chemotherapy involves taking medicines that kill cancer cells. You may receive just one type of medicine or a combination of medicines.

Most people with stage III colon cancer receive chemotherapy after surgery for 3 to 6 months. This is called adjuvant chemotherapy. Even though the tumor was removed, chemotherapy is given to treat any cancer cells that may remain.

Chemotherapy is also used to improve symptoms and prolong survival in people with stage IV colon cancer.


Immunotherapy involves taking medicines that increase the ability of your own immune system to destroy cancer cells. Immunotherapy has different side effects than chemotherapy.


Radiation therapy involves using radiation to kill cancer cells. Radiation therapy is often used in the treatment of rectal cancer.



For people with stage IV disease that has spread to the liver, treatment can be directed at the cancer tumors in the liver. This may include:

Outlook (Prognosis)

With treatment stages 0, I, II, and III cancers often are cured, although higher stages of cancer are less likely to be cured. In most cases stage IV cancer is not curable, but there are exceptions, including sometimes when the spread of the cancer is limited to the liver. In order for a person to be cured, treatment must get rid of all of the cancer. But there is a chance that the cancer will come back. If this occurs, curing the cancer is much less likely than before.

Cancer treatment can cause problems such as:

Possible Complications

Complications may include:

When to Contact a Medical Professional

Contact your provider if you have:


Colon cancer can almost always be caught by colonoscopy in early stages, when it is most curable. All adults age 45 and older should have a colon cancer screening. How often you should have screening depends upon the test being used.

Colon cancer screening can often find polyps before they become cancerous. Removing these polyps may prevent colon cancer.

People with certain risk factors for colon cancer may need earlier testing (before age 45) or more frequent testing.

A healthy lifestyle also may help reduce your risk for colon cancer:

Related Information

Hodgkin lymphoma
Colorectal polyps
Ulcerative colitis
Virtual colonoscopy
Total proctocolectomy and ileal-anal pouch
Total proctocolectomy with ileostomy
Chemotherapy - what to ask your doctor
Radiation therapy - questions to ask your doctor
Changing your ostomy pouch
Ileostomy - what to ask your doctor
Abdominal radiation - discharge
Pelvic radiation - discharge
Bland diet
Ileostomy and your child
Ileostomy and your diet
Ileostomy - caring for your stoma
Ileostomy - changing your pouch
Types of ileostomy
Ileostomy - discharge
Living with your ileostomy
Large bowel resection - discharge
Small bowel resection - discharge
Total colectomy or proctocolectomy - discharge


Centers for Disease Control and Prevention. What can I do to reduce my risk of colorectal cancer? Updated February 23, 2023. Accessed September 7, 2023.

National Cancer Institute website. Colorectal cancer prevention (PDQ) - health professional version. Updated August 18, 2023. Accessed September 7, 2023.

National Comprehensive Cancer Network website. NCCN clinical practice guidelines in oncology (NCCN Guidelines). Colorectal cancer screening. Version 1.2023 - May 17, 2023. Updated May 17, 2023. Accessed September 7, 2023.

Patel SG, May FP, Anderson JC, et al. Updates on age to start and stop colorectal cancer screening: recommendations from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2022;117(1):57-69. PMID: 34962727

Qaseem A, Crandall CJ, Mustafa RA, et al. Screening for colorectal cancer in asymptomatic average-risk adults: a guidance statement from the American College of Physicians. Ann Intern Med. 2019;171(9):643-654. PMID: 31683290

US Preventive Services Task Force, Davidson KW, Barry MJ, et al. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2021;325(19):1965-1977. PMID: 34003218


Review Date: 4/18/2023  

Reviewed By: John Roberts, MD, Professor of Internal Medicine (Medical Oncology), Yale Cancer Center, New Haven, CT. He is board certified in Internal Medicine, Medical Oncology, Pediatrics, Hospice and Palliative Medicine. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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