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Colorectal cancer

Definition

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.

Patient Education Video: Colon cancer

Alternative Names

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

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
  • Have inflammatory bowel disease (Crohn disease or ulcerative colitis)
  • 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:

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.

Colonoscopy
A sample of colon tissue is obtained during a colonoscopy procedure using special instruments. The specimen is sent to the laboratory and fixed with special stains. The specimen is examined under the microscope for abnormal findings, such as cancer or inflammation.

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

  • Complete blood count (CBC) to check for anemia
  • Liver function tests

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.

Barium enema
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.

Treatment

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

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
  • Cancer returning in the colon
  • Cancer spreading to other organs or tissues (metastasis)
  • 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.

Gallery

Barium enema
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.
Anal fissure - series
The anus is a sphincter at the end of the rectum through which passes stool during defecation. The anal sphincter is a critical mechanism for control of fecal continence.
Digestive system
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.
Barium enema
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.
Colonoscopy
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.
CT scan
CT stands for computerized tomography. In this procedure, a thin X-ray beam is rotated around the area of the body to be visualized. Using very complicated mathematical processes called algorithms, the computer is able to generate a 3-D image of a section through the body. CT scans are very detailed and provide excellent information for the physician.
Barium enema
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
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.
Colonoscopy
A sample of colon tissue is obtained during a colonoscopy procedure using special instruments. The specimen is sent to the laboratory and fixed with special stains. The specimen is examined under the microscope for abnormal findings, such as cancer or inflammation.
Barium enema
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.
The large intestine
The large intestine (or colon, or large bowel) is the last structure to process food, taking the undigestible matter from the small intestine, absorbing water from it and leaving the waste product called feces. Feces are expelled from the body through the rectum and the anus.
The large intestine
The large intestine (or colon, or large bowel) is the last structure to process food, taking the undigestible matter from the small intestine, absorbing water from it and leaving the waste product called feces. Feces are expelled from the body through the rectum and the anus.
Large intestine (colon)
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.

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.

Last reviewed January 25, 2022 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..

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Clinical Trials: Colorectal cancer

UF Health research scientists make medicine better every day. They discover new ways to help people by running clinical trials. When you join a clinical trial, you can get advanced medical care. Sometimes years before it's available everywhere. You can also help make medicine better for everyone else. If you'd like to learn more about clinical trials, visit our clinical trials page. Or click one of the links below:

Intervention using technology to reduce colorectal cancer disparities

The purpose of this proposal is to test the efficacy of a patient-centered, tailored message intervention delivered via virtual technology for increasing colorectal cancer (CRC) screening within guidelines among racial/ethnic minority and rural…

Status
Accepting Candidates
Ages
45 Years - 73 Years
Sexes
All
BLUE-C

The primary objective of this study is to assess the sensitivity for colorectal cancer (CRC) and specificity of the mt-sDNA 2.0 test.

Status
Accepting Candidates
Ages
40 Years - N/A
Sexes
All
View all colorectal cancer studies

Community and Patient Programs: Colorectal cancer

Our community and patient programs provide great value to patients, families and loved ones. People can find support, educational materials, expert consultants and more. In most instances, these programs are offered free of charge.

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