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.

Causes

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:

Are age 45 or older
Drink alcohol
Smoke tobacco
Are overweight or have obesity
Are African American or of eastern European descent
Eat a lot of red or processed meats
Eat a low-fiber and high-fat diet
Have a diet low in fruits and vegetables
Have colorectal polyps
Colorectal polyps
A colorectal polyp is a growth on the lining of the colon or rectum.
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Have inflammatory bowel disease (Crohn disease or ulcerative colitis)
Crohn disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
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Ulcerative colitis
Ulcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...
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Have a family history of colorectal cancer

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

Symptoms

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

Abdominal pain and tenderness in the lower abdomen
Abdominal pain and tenderness
Abdominal pain is pain that you feel anywhere between your chest and groin. This is often referred to as the stomach region or belly.
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Blood in the stool
Blood in the stool
Black or tarry stools with a foul smell are a sign of a problem in the upper digestive tract. It most often indicates that there is bleeding in the ...
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Diarrhea, constipation, or other change in bowel habits
Diarrhea
Diarrhea is when you pass loose or watery stool.
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Narrow stools
Weight loss with no known reason
Weight loss
Unexplained weight loss is a decrease in body weight, when you did not try to lose the weight on your own. Many people gain and lose weight. Uninten...

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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.

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

Complete blood count (CBC) to check for anemia
Complete blood count
A complete blood count (CBC) test measures the following:The number of white blood cells (WBC count)The number of red blood cells (RBC count)The numb...
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Liver function tests
Liver function tests
Liver function tests are common tests that are used to see how well the liver is working. Tests include:AlbuminAlpha-1 antitrypsinAlkaline phosphata...
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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:

Stage 0: Cancer is only on the innermost layer of the lining of the intestine
Stage I: Cancer is in the inner layers of the colon
Stage II: Cancer has spread through the muscle wall of the colon
Stage III: Cancer has spread to the lymph nodes
Stage IV: Cancer spread to other organs, such as the liver or lungs

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

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Treatment

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

Endoscopic surgery (less invasive surgery using a lighted, flexible tube)
Surgery
Chemotherapy
Chemotherapy
The term chemotherapy is used to describe cancer-killing drugs. Chemotherapy may be used to:Cure the cancerShrink the cancerPrevent the cancer from ...
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Radiation therapy
Radiation therapy
Radiation therapy uses high-powered radiation (such as x-rays or gamma rays), particles, or radioactive seeds to kill cancer cells.
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Immunotherapy
Immunotherapy
Immunotherapy is a type of cancer treatment that relies on the body's infection-fighting system (immune system). It uses substances made by the body...

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Targeted therapy
Targeted therapy
You are having a targeted therapy to try to kill cancer cells. You may receive targeted therapy alone or also have other treatments at the same time...

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SURGERY

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

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

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

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

TARGETED THERAPY

Targeted treatment zeroes in on specific targets (molecules) in cancer cells. These targets play a role in how cancer cells grow and survive. Using these targets, the drug disables the cancer cells so they cannot spread. Targeted therapy may be given as pills or may be injected into a vein.
You may have targeted therapy along with surgery, chemotherapy, or radiation treatment.

CANCER IN THE LIVER

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:

Burning the liver tumors (ablation)
Delivering chemotherapy or radiation directly into the liver
Freezing the liver tumors (cryotherapy)
Surgery
Radioactive beads/spheres that deliver treatment to kill the cancer cells
Alcohol (ethanol) injected into the liver tumors to kill cancer cells

Support Groups

You can ease the stress of the disease by joining a colon cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.

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:

Bowel obstruction from surgical scarring.
Many sorts of short- and long-term side effects from chemotherapy, immunotherapy, radiation, and therapy targeted to the liver.

Possible Complications

Complications may include:

Blockage of the colon, causing bowel obstruction
Bowel obstruction
Intestinal obstruction is a partial or complete blockage of the bowel. The contents of the intestine cannot pass through it.
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Cancer returning in the colon
Cancer spreading to other organs or tissues (metastasis)
Metastasis
Metastasis is the movement or spreading of cancer cells from one organ or tissue to another. Cancer cells usually spread through the blood or the ly...
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Development of a second primary colorectal cancer

When to Contact a Medical Professional

Contact your provider if you have:

Black, tar-like stools
Blood during a bowel movement
Change in bowel habits
Unexplained weight loss

Prevention

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:

Get regular physical activity.
Don't smoke or use tobacco.
Maintain a healthy weight.
Eat a diet rich in fruits and vegetables and low in red and processed meats.

Open References

References

Centers for Disease Control and Prevention website. Reducing risk for colorectal cancer. www.cdc.gov/colorectal-cancer/prevention/. Updated June 20, 2024. Accessed August 27, 2024.

Garber JJ, Chung DC. Colonic polyps and polyposis syndromes. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 126.

Lawler M, Johnston B, Van Schaeybroeck S, et al. Colorectal cancer. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 74.

National Cancer Institute website. Colorectal Cancer Prevention (PDQ) - Health Professional Version. www.cancer.gov/types/colorectal/hp/colorectal-prevention-pdq. Updated March 28, 2024. Accessed August 27, 2024.

National Comprehensive Cancer Network website. NCCN clinical practice guidelines in oncology (NCCN guidelines): colorectal cancer screening. Version 1.2024 - February 27, 2024. www.nccn.org/professionals/physician_gls/pdf/colorectal_screening.pdf. Updated February 27, 2024. Accessed August 27, 2024.

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 pubmed.ncbi.nlm.nih.gov/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 pubmed.ncbi.nlm.nih.gov/31683290/.

US Preventive Services Task Force website. Final recommendation statement. Colorectal cancer: screening. www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening. Published May 18, 2021. Accessed February 11, 2024.

Barium enema - illustration
The barium enema is a valuable diagnostic tool that helps detect abnormalities in the large intestine (colon). The barium enema, along with colonoscopy, remain standards in the diagnosis of colon cancer, ulcerative colitis, and other diseases of the colon.
Barium enema
illustration
Colonoscopy - illustration
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
Colonoscopy
illustration
Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.
Digestive system
illustration
Rectal cancer - X-ray - illustration
A barium enema in a patient with cancer of the rectum.
Rectal cancer - X-ray
illustration
Sigmoid colon cancer - X-ray - illustration
A barium enema in a patient with cancer of the large bowel (sigmoid area).
Sigmoid colon cancer - X-ray
illustration
Spleen metastasis - CT scan - illustration
This CT scan of the upper abdomen shows multiple tumors in the liver and spleen that have spread (metastasized) from an original intestinal cancer (carcinoma).
Spleen metastasis - CT scan
illustration
Structure of the colon - illustration
The large intestine is a long hollow organ lined with mucous membrane (mucosa). Muscle layers wrap around the entire length and help move food material through to the rectum.
Structure of the colon
illustration
Stages of cancer - illustration
The staging of a carcinoma has to do with the size of the tumor, and the degree to which it has penetrated. When the tumor is small and has not penetrated the mucosal layer, it is said to be stage I cancer. Stage II tumors are into the muscle wall, and stage III involves nearby lymph nodes. The rare stage IV cancer has spread (metastasized) to remote organs.
Stages of cancer
illustration
Colon culture - illustration
When polyps are discovered in a sigmoidoscopy (an inspection of the lower third of the large intestine), they are retrieved to be tested for cancer. If a large amount of polyps are found, a more thorough examination of the entire length of the large intestine (a colonoscopy) may be recommended.
Colon culture
illustration
Colon cancer - Series
Presentation

<strong>Colon cancer - series</strong><p>The colon, or large intestine, is a muscular tube that begins at the end of the small intestine and ends at the rectum. The colon absorbs water from liquid stool that is delivered to it from the small intestine.</p>

<strong>Indication</strong><p>Colon cancer is the third most common cancer in the United States. Risk factors include a diet low in fiber and high in fat, certain types of colonic polyps, inflammatory bowel disease (such as Crohn disease or ulcerative colitis), and certain hereditary disorders.</p>

<strong>Incision</strong><p>The treatment of colon cancer depends on the stage of the disease. Stage I cancer is limited to the inner lining of the colon; Stage II cancer involves the entire wall of the colon; Stage III cancer has spread to the lymph nodes; Stage IV cancer has spread to other organs (metastasized).</p>

<strong>Procedure</strong><p>Surgery is the main treatment for colon cancer and removal of the involved colon is required. If the cancer is located near the rectum, a colostomy may be necessary. For stage I and II colon cancer, surgery is usually the only treatment. For stage III or IV colon cancer, chemotherapy is necessary after surgery. There is also some suggestion that chemotherapy may also be helpful in some selected stage II patients. Chemotherapy involves a course of drugs which are toxic to cancer cells.</p>

<strong>Aftercare</strong><p>Stage I and II colon cancer have very high cure rates (60% to 90%); lower cure rates are seen with stage III and IV colon cancer. To detect colon cancer early, when it is most curable, everyone over the age of 55 should have bi-annual endoscopic examinations of the colon.</p>

Colostomy - Series
Presentation

<strong>Colostomy - series</strong><p>The colon, or large intestine, is a digestive organ located in the abdomen. The large intestine begins at the end of the small intestine and extends through the rectum and anus.</p>

<strong>Indications</strong><p>A colostomy is done when the lower large intestine, rectum, or anus is unable to function normally or needs rest from normal functions. Intestinal obstruction with associated inflammation, as in diverticulitis, is a common indication for colostomy.</p>

<strong>Procedure, part 1</strong><p>A colostomy creates an opening on the abdomen (stoma) for the drainage of stool (feces) from the large intestine (colon). Colostomies are usually performed after the diseased colon has been removed. Colostomies may be temporary or permanent. While the patient is deep asleep and pain-free (general anesthesia), an incision is made in the abdomen. The diseased colon is removed.</p>

<strong>Procedure, part 2</strong><p>The proximal end of the healthy colon is then brought out to the skin of the abdominal wall, where it is sutured in place. An adhesive drainage bag (stoma appliance) is placed around the opening. The abdominal incision is then closed.</p>

<strong>Aftercare</strong><p>In more than 90% of the cases, the surgery is successful. The patient may experience considerable pain after surgery as the anus tightens and relaxes. Medications to relieve pain may be used. To avoid straining, stool softeners will be used. Avoid any straining during bowel movement or urination. Soaking in a warm bath can bring additional comfort. Depending on the disease process being treated, colostomies can be taken down and the colon reconnected in a second operation within weeks to months after the first operation.</p>

Large bowel resection - Series
Presentation

<strong>Large bowel resection - series</strong><p>The large bowel [large intestine or the colon] is part of the digestive system. It runs from the small intestine to the rectum. It is made up of three portions; the ascending, transverse and descending colon. The ascending colon is sometimes referred to as the right colon; the descending colon is sometimes referred to as the left, or sigmoid colon.</p>

<strong>Indications</strong><p>Bowel resection may be indicated for blockage of the intestine (intestinal obstruction) due to scar tissue or tumors, bleeding, due to diverticulosis or arteriovenous malformations, injuries, cancer, precancerous polyps, familial polyposis, and infection, due to diverticulitis.</p>

<strong>Incision</strong><p>The patient is deep asleep and pain-free (general anesthesia). A lower midline incision is made in the abdomen. Sometimes, the surgeon will use a lateral lower transverse incision instead.</p>

<strong>Procedure, part 1</strong><p>The diseased part of the large intestine (colon) is removed. The two healthy ends are then sewn or stapled back together and the incision is closed. A stapling procedure is shown here.</p>

<strong>Procedure, part 2</strong><p>If it is necessary to spare the intestine from its normal digestive work while it heals, a temporary opening of the intestine onto the abdomen (colostomy) may be done. A temporary colostomy will be closed and repaired later. If a large portion of the bowel is removed, the colostomy may be permanent. The large intestine (colon) absorbs most of the fluid from foods. When the colon is bypassed by a colostomy in the right colon, the colostomy output is generally liquid stool (feces). If the colon is bypassed in the left colon, the colostomy output is generally more solid stool. The constant or frequent drainage of liquid stool can cause the skin around the colostomy to become inflamed. Careful skin care and a well-fitting colostomy bag can reduce this irritation.</p>

<strong>Aftercare</strong><p>Most patients will stay in the hospital for 5 to 7 days. Complete recovery from surgery may take 2 months. During the first few days after surgery, eating is restricted.</p>

Large intestine (colon) - illustration
The large intestine is the portion of the digestive system most responsible for absorption of water from the indigestible residue of food. The ileocecal valve of the ileum (small intestine) passes material into the large intestine at the cecum. Material passes through the ascending, transverse, descending and sigmoid portions of the colon, and finally into the rectum. From the rectum, the waste is expelled from the body.
Large intestine (colon)
illustration

Barium enema - illustration
The barium enema is a valuable diagnostic tool that helps detect abnormalities in the large intestine (colon). The barium enema, along with colonoscopy, remain standards in the diagnosis of colon cancer, ulcerative colitis, and other diseases of the colon.
Barium enema
illustration
Colonoscopy - illustration
There are 3 basic tests for colon cancer; a stool test (to check for blood), sigmoidoscopy (inspection of the lower colon), and colonoscopy (inspection of the entire colon). All 3 are effective in catching cancers in the early stages, when treatment is most beneficial.
Colonoscopy
illustration
Digestive system - illustration
The esophagus, stomach, large and small intestine, aided by the liver, gallbladder and pancreas convert the nutritive components of food into energy and break down the non-nutritive components into waste to be excreted.
Digestive system
illustration
Rectal cancer - X-ray - illustration
A barium enema in a patient with cancer of the rectum.
Rectal cancer - X-ray
illustration
Sigmoid colon cancer - X-ray - illustration
A barium enema in a patient with cancer of the large bowel (sigmoid area).
Sigmoid colon cancer - X-ray
illustration
Spleen metastasis - CT scan - illustration
This CT scan of the upper abdomen shows multiple tumors in the liver and spleen that have spread (metastasized) from an original intestinal cancer (carcinoma).
Spleen metastasis - CT scan
illustration
Structure of the colon - illustration
The large intestine is a long hollow organ lined with mucous membrane (mucosa). Muscle layers wrap around the entire length and help move food material through to the rectum.
Structure of the colon
illustration
Stages of cancer - illustration
The staging of a carcinoma has to do with the size of the tumor, and the degree to which it has penetrated. When the tumor is small and has not penetrated the mucosal layer, it is said to be stage I cancer. Stage II tumors are into the muscle wall, and stage III involves nearby lymph nodes. The rare stage IV cancer has spread (metastasized) to remote organs.
Stages of cancer
illustration
Colon culture - illustration
When polyps are discovered in a sigmoidoscopy (an inspection of the lower third of the large intestine), they are retrieved to be tested for cancer. If a large amount of polyps are found, a more thorough examination of the entire length of the large intestine (a colonoscopy) may be recommended.
Colon culture
illustration
Colon cancer - Series
Presentation

Colostomy - Series
Presentation

Large bowel resection - Series
Presentation

Large intestine (colon) - illustration
The large intestine is the portion of the digestive system most responsible for absorption of water from the indigestible residue of food. The ileocecal valve of the ileum (small intestine) passes material into the large intestine at the cecum. Material passes through the ascending, transverse, descending and sigmoid portions of the colon, and finally into the rectum. From the rectum, the waste is expelled from the body.
Large intestine (colon)
illustration

A Closer Look

Colorectal cancer

Talking to your MD

Self Care

Tests for Colorectal cancer

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. Internal review and update on 02/20/2024 by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 08/27/2024.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Health Library

Colorectal cancer

Causes

Noncancerous (benign) lumps (polyps)

Colorectal polyps

Crohn disease

Ulcerative colitis

Symptoms

Abdominal pain and tenderness

Blood in the stool

Diarrhea

Weight loss

Exams and Tests

Screening tests, colon cancer

Complete blood count

Liver function tests

Staging

CT

MRI

PET

Carcinoembryonic antigen (CEA)

Treatment

Chemotherapy

Radiation therapy

Immunotherapy

Targeted therapy

Colon resection

Spread to the liver

Support Groups

Colon cancer support group

Outlook (Prognosis)

Possible Complications

Bowel obstruction

Metastasis

When to Contact a Medical Professional

Prevention

Healthy lifestyle

References

Barium enema - illustration

Barium enema

Colonoscopy - illustration

Colonoscopy

Digestive system - illustration

Digestive system

Rectal cancer - X-ray - illustration

Rectal cancer - X-ray

Sigmoid colon cancer - X-ray - illustration

Sigmoid colon cancer - X-ray

Spleen metastasis - CT scan - illustration

Spleen metastasis - CT scan

Structure of the colon - illustration

Structure of the colon

Stages of cancer - illustration

Stages of cancer

Colon culture - illustration

Colon culture

Colon cancer - Series

Colostomy - Series

Large bowel resection - Series

Large intestine (colon) - illustration

Large intestine (colon)