Colorectal cancer

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

Colorectal cancer is cancer that starts in the large intestine (colon) or the rectum (end of the colon).

Other types of cancer can affect the colon. These include lymphoma, carcinoid tumors, melanoma, and sarcomas. These are rare. In this article, colon cancer refers to colorectal cancer only.

Causes

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.

Almost all colon cancers start in the lining of the colon and rectum. When doctors talk about colorectal cancer, this is usually what they are talking about.

There is no single cause of colon cancer. Nearly all colon cancers begin as noncancerous (benign) polyps, which slowly develop into cancer.

You have a higher risk for colon cancer if you:

Are older than 45
Drink alcohol
Smoke tobacco
Are obese
Are African American or of eastern European descent
Eat a lot of red or processed meats
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 colon cancer

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

What you eat may play a role in getting colon cancer. Colon cancer may be linked to a high-fat, low-fiber diet and to a high intake of red meat. Some studies have found that the risk does not drop if you switch to a high-fiber diet, so this link is not yet clear.

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.

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

Certain tests used to screen for colon cancer may suggest colon cancer. A sigmoidoscopy, or more likely, a colonoscopy, will be done to evaluate any normal results.

Only a full colonoscopy can see the entire colon. This is the best screening test for 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 red blood cells (RBC count)The number of white blood cells (WBC count)The tota...
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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 colon cancer are:

Stage 0: Very early cancer on the innermost layer 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 has spread to other organs outside the colon

Blood tests to detect tumor markers, such as carcinoembryonic antigen (CEA) may help the doctor follow you during and after treatment.

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Treatment

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

Surgery to remove the tumor
Chemotherapy to kill cancer cells
Chemotherapy
The term chemotherapy is used to describe cancer-killing drugs. Chemotherapy may be used to:Cure the cancer Shrink the cancerPrevent the cancer from...
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Radiation therapy to destroy cancerous tissue
Radiation therapy
Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells.
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Targeted therapy to keep cancer from growing and spreading
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 colonoscopy. For stages I, II, and III cancer, more extensive surgery is needed to remove the part of the colon that is cancerous. This surgery is called colon resection (colectomy).

CHEMOTHERAPY

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.

You may receive just one type of medicine or a combination of medicines.

RADIATION

Radiation therapy is sometimes used for colon cancer.

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

Burning the cancer (ablation)
Delivering chemotherapy or radiation directly into the liver
Freezing the cancer (cryotherapy)
Surgery

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.

Support Groups

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

Outlook (Prognosis)

In many cases, colon cancer is treatable when caught early.

How well you do depends on the stage of the cancer and other factors. When treated at an early stage, many people survive at least 5 years after diagnosis. This is called the 5-year survival rate.

If the colon cancer does not come back (recur) within 5 years, it is considered cured. Stages I, II, and III cancers are possibly curable. In most cases, stage IV cancer is not thought to be curable, but there are exceptions.

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

Call your health care 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

National Cancer Institute website. Colorectal cancer prevention (PDQ) - health professional version. www.cancer.gov/types/colorectal/hp/colorectal-prevention-pdq. Updated April 21, 2022. Accessed April 28, 2022.

National Comprehensive Cancer Network website. NCCN clinical practice guidelines in oncology (NCCN Guidelines). Colorectal cancer screening. Version 1.2022 - March 4, 2022. https://www.nccn.org/professionals/physician_gls/pdf/colorectal_screening.pdf. Updated March 4, 2022. Accessed April 28, 2022.

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/.

Rex DK, Boland CR, Dominitz JA, et al. Colorectal cancer screening: recommendations for physicians and patients from the U.S. Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol. 2017;112(7):1016-1030. PMID: 28555630 pubmed.ncbi.nlm.nih.gov/28555630/.

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 April 28, 2022.

Colon cancer
Animation

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

Colon cancer
Animation

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

Talking to your MD

Self Care

Tests for Colorectal cancer

Review Date: 1/25/2022

Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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. © 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

Lymphoma

Melanoma

Causes

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

Sigmoidoscopy

Colonoscopy

Complete blood count

Liver function tests

Staging

CT

MRI

PET

Carcinoembryonic antigen (CEA)

Treatment

Chemotherapy

Radiation therapy

Targeted therapy

Colon resection

Support Groups

Colon cancer support group.

Outlook (Prognosis)

Possible Complications

Bowel obstruction

Metastasis

When to Contact a Medical Professional

Prevention

References

Colon cancer

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)

Colon cancer

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