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UC Davis Health System

UC Davis Health System

Checkup on Health: Don't put off screening for colorectal cancer

older man on telephone
Every American should undergo regular screening tests for colorectal cancer starting at the age of 50. African-Americans are especially at high risk and should not delay screening. 

By Vijay P. Khatri, M.D. 

Colorectal cancer has taken a front-page position in the news in recent years, with well-known personalities discussing their battles with the disease. Have you regarded this as just one more celebrity fad? You shouldn’t.

Consider this:

  • Colorectal cancer (cancer found either in the colon or rectum) is one of the three most common causes of cancer deaths in the U.S.

  • More than 90 percent of colorectal cancers can be cured when caught in the earliest stages, before symptoms appear.

  • Most experts recommend that every American, starting at the age of 50, should undergo regular screening tests for this disease.

Common symptoms

About the author

Dr. Khatri is a surgical oncologist with UC Davis Medical Center and UC Davis Cancer Center in Sacramento. 

Colorectal cancer develops from cells lining the large intestine. Sometimes cells grow into abnormal collections and bud off into polyps. Also called adenomas or adenomatous polyps, these growths occur in about 40 percent of Americans by age 50. Although they are benign, about 25 percent of them will eventually become cancerous if not removed.

A cancerous growth may invade into or through the muscular wall of the intestine, or spread through the lymphatic system or the bloodstream to other parts of the body. At this stage, the chance of cure is much reduced.

Our best approach is to find the polyps before they have reached this point and remove them.

Screening

Experts recommend that a combination of several screening procedures for colorectal cancer be done on a regular basis for healthy individuals over the age of 50. They include:

  • A fecal occult blood test. A bit of stool is placed on chemically treated paper, indicating the presence of iron, a component of blood. Certain foods, such as red meat, should be avoided during the three-day period in which this test is done. This test alone has been found to reduce cancer mortality rates by 20 percent. 

  • A flexible sigmoidoscopy. A flexible tube attached to a fiber optic light system is passed into the rectum so that the lower third to half of the colorectum can be visualized. It should be done once every five years starting at age 50. Because only part of the colorectum is examined, this test should be combined with a double contrast barium enema exam.

  • A double contrast barium enema exam, a series of X-rays taken after administering air plus an enema of a white, chalky solution. It enables the colon’s lining and any abnormalities to be visualized. Done alone, it is not as trustworthy as the sigmoidoscopy or colonoscopy, but is a reasonable alternative for people unable to undergo those more invasive procedures. For those individuals, it should be used as a screening test every 5 to 10 years.

  • A colonoscopy, which is similar to a sigmoidoscopy, but allows the entire colon to be examined. If a polyp is seen, the doctor can biopsy it and remove it during the exam. It should be used if anything suspicious is found in the other tests and as a general screening tool about once every 10 years in people without risk factors and more frequently for those at high risk.

Do these sound unpleasant? Well most people would prefer to do other things, and it turns out that less than one third of people who should be screened actually do so. But screening does save lives, and of course, is far easier than coping with cancer!

Increased risk

Dr. Khatri"Less than one-third of people who should be screened actually do so — but screening does save lives, and of course, is far easier than coping with cancer."

— Vijay Khatri

People who are at an increased risk for colorectal cancer should be screened more thoroughly, more frequently and starting at an earlier age. Significant risk factors include:

  • Having a close relative (a son, daughter, parent or sibling) who was diagnosed with either adenomas or colorectal cancer before the age of 50.

  • A personal history of adenomas, as well as breast or gynecological cancers.

  • Inflammatory bowel disease, including Crohn’s disease or ulcerative colitis.

Of course, anyone who has any symptoms of colorectal cancer should also be thoroughly worked up at once, regardless of age. Symptoms include blood in the stool (either red or black), persistent diarrhea, constipation, bloating or cramps, or pencil-thin stools. Unexplained weight loss or excessive fatigue should also be checked out.

No one knows for sure why Americans tend to develop colorectal cancer in such high numbers, but diet and lifestyle are strongly suspected. As is true for many other health problems, people who eat less red meat and large amounts of fiber (found in fruits, vegetables and many cereals), nonsmokers, and those who exercise regularly have lower rates of the disease. African-Americans are especially at high risk and should not delay screening. 

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