HealthHints

Colorectal Cancer –
Screening for life

June 2010 – Vol. 14, No. 6

Editor: Janet M. Pollard, MPH

“Colorectal cancer is the third most common type of non-skin cancer in men (after prostate cancer and lung cancer) and in women (after breast cancer and lung cancer).”1 It is the second leading cancer killer (after lung cancer1) in the United States, but it doesn’t have to be.2

About 1 in 15 people develop colorectal cancer.3 Colorectal cancer can be a life-threatening condition that affects the large intestine, but if it is found early, it is a highly curable form of cancer.3 “If everyone 50 years or older had regular screening tests, at least 60 percent of deaths from this cancer could be avoided.” Individuals at higher risk for colorectal cancer may need to begin screening at an earlier age.4 “The best time to get screened is before any symptoms appear.”4 Screening for colorectal cancer can save lives.2,5

What is Colorectal Cancer? The digestive system and cancer cells

Colorectal cancer occurs in the colon or rectum (sometimes just called colon cancer2). “The colon and rectum are parts of the body’s digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the mouth, throat, esophagus, stomach, and the small and large intestines.6 The first 6 feet of the large intestine are called the large bowel or colon. The last 6 inches are the rectum and the anal canal. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).”6

“The body is made up of many types of cells. Normally, cells grow, divide, and then die. Sometimes, cells mutate (change) and begin to grow and divide more quickly than normal cells. Rather than dying, these abnormal cells clump together to form tumors. If these tumors are cancerous (also called malignant tumors), they can invade and kill your body’s healthy tissues. From these tumors, cancer cells can metastasize (spread) and form new tumors in other parts of the body. By contrast, noncancerous tumors (also called benign tumors) do not spread to other parts of the body.”7 “Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells called adenomatous polyps. Over time, some of these polyps become colon cancers. Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying polyps before they become colon cancer.”8

Symptoms of Colorectal Cancer: No symptoms in early stages

“Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in your large intestine.”8 Signs and symptoms of colorectal cancer may include:

  • a change in your bowel habits, including diarrhea or constipation or a change in the shape (i.e., narrow stools) or consistency of your stool for more than a couple of weeks;
  • rectal bleeding or blood in your stool or in the toilet after you have a bowel movement;
  • persistent abdominal discomfort (pain or tenderness), such as cramps, gas, or pain in your lower stomach;
  • a feeling of discomfort or urge to have a bowel movement when there is no need to have one or a feeling that your bowel doesn’t empty completely;
  • weakness or fatigue;
  • unexplained/unintended weight loss;
  • unexplained anemia.7,8,9

“If you notice any symptoms of colon cancer, such as blood in your stool or a persistent change in bowel habits, make an appointment with your doctor. Talk to your doctor about when you should begin screening for colon cancer. Guidelines (PDF) generally recommend colon cancer screenings begin at age 50. Your doctor may recommend more frequent or earlier screening if you have other risk factors, such as a family history of the disease.”8

Screening Tests: Who?

Colon cancer is more common in older people, with 93 percent of cases occurring in persons 50 years of age or older.10 Men and women at average risk for colorectal cancer should begin colorectal cancer screening at age 50. There are some other factors, however, that put an individual at higher risk for developing colorectal cancer. These individuals may need earlier or more frequent screening.11

Factors that increase your risk for developing colorectal cancer include:

  • being of African American or eastern European descent;9
  • having inflammatory bowel disease (Crohn’s disease or ulcerative colitis [ulcers in the lining of the large intestine]);
  • having a personal history of colorectal cancer or polyps;
  • having a personal history of cancer of the ovary, endometrium, or breast;
  • having a family history of colon cancer or polyps;
  • having hereditary conditions known as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC, also called Lynch Syndrome).12

Screening Tests: Why?

“Getting a colorectal cancer screening test could save your life. Here’s how:

  • Colorectal cancer usually starts from polyps in the colon or rectum. A polyp is a growth that shouldn’t be there.
  • Over time, some polyps can turn into cancer.
  • Screening tests can find polyps, so they can be removed before they turn into cancer.
  • Screening tests also can find colorectal cancer early. When it is found early, the chance of being cured is good.”2

“Precancerous polyps and early-stage colorectal cancer don’t always cause symptoms, especially at first. This means that someone could have polyps or colorectal cancer and not know it. That is why having a screening test is so important.”2 Talk with your doctor about when to begin screening and how often if you have any of these risk factors.

Screening Tests: What Type?

“Screening is the process of looking for cancer in people who have no symptoms.”13 “Several different screening tests can be used to find polyps or colorectal cancer. Each can be used alone. Sometimes they are used in combination with each other.”2

Fecal occult blood test (FOBT) [PDF].
“A fecal occult blood test is a test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing. Blood in the stool may be a sign of polyps or cancer.”6 “There are two types of FOBT. One test uses a chemical called guaiac to detect blood in your stool. The other – a fecal immunochemical test (FIT) – uses antibodies to detect blood in the stool. You will receive a test kit from your health care provider. At home, you use a stick or brush to obtain a small amount of stool. You return the test to the doctor or a lab, where stool samples are checked for blood.2

Stool DNA test [PDF].
Instead of looking for blood in the stool, this test checks for cells that are shed by colon cancers or precancerous polyps.7 Colorectal cancer cells often contain DNA (genetic material) mutations (changes) in certain genes. Cells from colorectal cancers or polyps with these mutations are often shed in the stool where tests may be able to detect them.13 Your doctor will give you a test kit with instructions on collecting an entire bowel movement, which will be sent to a lab.2,7

Sigmoidoscopy [PDF].
“Sigmoidoscopy [also called flexible sigmoidoscopy] is a procedure to look inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer.”6 For this test, the doctor puts a short, thin, flexible, lighted tube with a lens for viewing into your rectum. It may also have a tool to remove polyps or tissue samples, which are checked under a microscope for signs of cancer.13

Colonoscopy [PDF].
This test is similar to sigmoidoscopy, except the doctor uses a longer, thin, flexible, lighted tube to check for polyps or cancer inside the rectum and the entire length of the colon. During the test, the doctor can find and remove most polyps and some cancers.2

Virtual colonoscopy [PDF].
This test uses a series of x-rays (called computed tomography [CT]) to examine the inside of the colon. A computer is used to make detailed 2-dimensional (2-D) and 3-D pictures of the colon.6 Instead of one picture, like an x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table.13 These images may show polyps and anything else that seems unusual on the inside surface of the colon.6

Double contrast barium enema (DCBE) [PDF].
A barium enema is a series of x-rays of the lower gastrointestinal tract, sometimes called a lower GI series.6 A liquid that contains barium (a silver-white metallic compound) and air are put into the rectum. The barium coats the lower gastrointestinal tract and outlines the inner part of the colon and rectum to look for abnormal areas.6,13

Digital rectal exam (DRE) [PDF].
This test is an exam of the rectum. “The doctor or nurse inserts a lubricated, gloved finger into the lower part of the rectum to feel for lumps or anything else that seems unusual.”6

Talk with your doctor about which test(s) is right for you. For more about each procedure and its advantages and disadvantages, see Weighing the Pros & Cons of Colorectal Cancer Screening (PDF).

Screening Tests: When?

“Several major organizations, including the U.S. Preventive Services Task Force (PDF) (a group of experts convened by the U.S. Public Health Service), the American Cancer Society (PDF), the U.S. Multi-Society Task Force on Colorectal Cancer (PDF), and the American College of Radiology (PDF), have developed guidelines (PDF) for colorectal cancer screening. Although some details of their recommendations vary regarding which screening tests to use and how often to be screened, all of these organizations support screening for colorectal cancer beginning at age 50 for average-risk adults, with earlier and/or more frequent screenings for those in higher-risk groups.”1 For higher-risk groups, see Colon Cancer Screening Guidelines recommended here.

“The decision to have a certain test will take into account several factors, including the following:

  • the person’s age, medical history, family history, and general health;
  • the accuracy of the test;
  • the potential harms of the test;
  • the preparation required for the test;
  • whether sedation is necessary during the test;
  • the follow-up care after the test;
  • the convenience of the test; and
  • the cost of the test and the availability of insurance coverage (PDF).”1

Talk to your doctor about when to start screening, which test(s) is right for you, and how often you should have them.

Screening Tests: How to prepare?

Before you have any of the screening tests, it is important to be prepared. Make sure you’ve talked with your doctor and had all your questions satisfactorily answered. Ask about any restrictions in your diet prior to the test, and be sure to inform your doctor about any medications you are taking. Find out if sedation is required or recommended with your test and, if so, plan for someone to drive you home. You will also want to know if your insurance (PDF) covers the cost of the procedure.

Here is some information about each test from the American Cancer Society14 that may help you prepare. Click on each procedure name below to learn more about how to prepare, what happens during the procedure, and any potential complications or side effects.

Screening Tests: Finding a doctor

Once you decide to be screened, be sure you are seeing a trained doctor. Your primary doctor may need to refer you to other specialists for the actual screening test(s).

For stool tests such as FOBT or FIT, your primary care doctor can provide you with a kit to take home to collect a stool sample. Be aware that a stool sample taken in a clinic or doctor’s office is not an appropriate screening for colorectal cancer. Stool sampling should be done with a “take-home” kit and should be repeated 2–3 times for accurate diagnosis. If these tests have positive results, your doctor may refer you to a gastroenterologist – a doctor who specializes in diagnosing and treating disorders of the digestive system.15

If you are having a procedure that involves endoscopy (such as sigmoidoscopy or colonoscopy), be sure your doctor is properly trained in such procedures. “More than 11,000 domestic and international gastroinenterologists, surgeons, and other medical specialists are expertly trained in endoscopy.”16

Both double contrast barium enema and virtual colonoscopy are usually done in the radiology department. A radiologic technologist and/or radiologist – a physician specifically trained to supervise and interpret radiology examinations – may guide the patient through these procedures. A radiologist will analyze the images and send a signed report to your primary care or referring physician, who will discuss the results with you.17,18

If you need help finding a doctor, you can call the American Cancer Society (1-800-ACS-2345) or National Cancer Institute (1-800-4- CANCER) for live help.

“Getting a colorectal cancer screening test could save your life.”2 Talk with your doctor about when to begin screening, which screening test or tests are right for you, and how often you should be screened. Then follow through, and get screened for life.

This document is meant for educational purposes only and is not intended to replace the advice of your doctor or other health care provider.

References:

  1. National Cancer Institute (2008). Colorectal cancer screening [online]. Retrieved April 12, 2010. From http://www.cancer.gov/cancertopics/factsheet/Detection/colorectal-screening.
  2. U.S. Department of Health and Human Services Centers for Disease Control and Prevention (2009). Colorectal cancer screening [online]. Retrieved April 12, 2010. From http://www.cdc.gov/cancer/colorectal/pdf/Basics_FS_Eng_Color.pdf.
  3. National Library of Medicine, National Institutes of Health (2007). X-plain colon cancer reference summary [online]. Retrieved April 12, 2010. From http://www.nlm.nih.gov/medlineplus/tutorials/coloncancer/oc069103.pdf.
  4. Prevent Cancer Foundation (2009). About colorectal cancer: Colorectal cancer 2009 fact sheet [online]. Retrieved April 8, 2010. From http://www.preventcancer.org/education3c.aspx?id=1036.
  5. American Society for Gastrointestinal Endoscopy (2010). Colorectal cancer [online]. Retrieved May 4, 2010. From http://www.screen4coloncancer.org/.
  6. National Cancer Institute (2009). Colorectal cancer screening (PDQ): Patient version [online]. Retrieved April 8, 2010. From http://www.cancer.gov/cancertopics/pdq/screening/colorectal/patient/allpages/print.
  7. American Academy of Family Physicians (2008). Colorectal cancer screening [online]. Retrieved April 8, 2010. From http://familydoctor.org/online/famdocen/home/common/cancer/risk/556.html.
  8. Mayo Clinic (2009). Colon cancer [online]. Retrieved April 8, 2010. From http://www.mayoclinic.com/health/colon-cancer/DS00035.
  9. National Library of Medicine, National Institutes of Health (2009). Colon cancer [online]. Retrieved April 8, 2010. From http://www.nlm.nih.gov/medlineplus/ency/article/000262.htm.
  10. American College of Gastroenterology (2007). Colorectal cancer screening [online]. Retrieved April 12, 2010. From http://www.gi.org/patients/gihealth/colon.asp.
  11. National Library of Medicine, National Institutes of Health (2009). Colon cancer screening [online]. Retrieved April 12, 2010. From http://www.nlm.nih.gov/medlineplus/ency/article/002071.htm.
  12. National Cancer Institute (2009). General information about colon cancer [online]. Retrieved April 29, 2010. From http://www.cancer.gov/cancertopics/pdq/treatment/colon/Patient.
  13. American Cancer Society (2010). Colon and rectum cancer detailed guide [online]. Retrieved April 8, 2010. From http://documents.cancer.org/107.00/107.00.pdf.
  14. American Cancer Society (2010). Can colorectal polyps and cancer be found early? [online]. Retrieved April 12, 2010. From http://www.cancer.org/docroot/CRI/content/CRI_2_4_3x_
    Can_Colon_and_rectum_cancer_be_found_early.asp.
  15. U.S. Department of Health and Human Services Centers for Disease Control and Prevention, Healthcare Financing Administration, National Cancer Institute (1999). Colorectal cancer: Let’s break the silence [online]. Retrieved April 12, 2010. From http://www.medicare.gov/Publications/Pubs/pdf/coloeng.pdf.
  16. American Society for Gastrointestinal Endoscopy (2010). Find a colorectal cancer doctor [online]. Retrieved May 4, 2010. From http://www.screen4coloncancer.org/physicianLocator.asp.
  17. American College of Radiology, Radiological Society of North America (2010). Lower gastrointestinal (GI) tract x-ray (radiography) [online]. Retrieved May 19, 2010.
    From http://www.radiologyinfo.org/en/info.cfm?pg=lowergi.
  18. National Institute of Diabetes and Digestive and Kidney Diseases (2008). Virtual colonoscopy [online]. Retrieved May 19, 2010. From http://digestive.niddk.nih.gov/ddiseases/pubs/virtualcolonoscopy/#how.

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Last updated: 26 July, 2010

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