Colon Cancer Early Detection Helps Improve Outcome

March Is National Colorectal Cancer Awareness Month

Colorectal cancers are thought to develop slowly over a period of several years, experts say. And, it is commonly known that most colorectal cancers begin as a polyp, also known as an adenoma.

Over many years (usually about five to 10), these polyps can slowly change into cancer.

Excluding skin cancers, colorectal cancer is the third most common cancer diagnosed in both men and women in the US.

The American Cancer Society estimates that about 106,370 new cases of colon cancer (50,400 men and 55,970 women) and 40,570 new cases of rectal cancer (23,220 men and 17,350 women) will be diagnosed in 2004.

Colorectal cancer is expected to cause about 56,730 deaths (28,320 men and 28,410 women) during 2004, accounting for about 10 percent of cancer deaths.

"The biggest thing people can do to reduce risk is to be screened," says Dr. David A. Johnson, chief of gastroenterology at the Eastern Virginia School of Medicine in Norfolk. "It's critical."

Given that March is National Colorectal Cancer Awareness Month, now could be a good time to look into screening.

Taking the Right Steps

Early detection makes the difference in the outcome of colorectal cancer, according to the American Cancer Society.

When the cancer is detected in a localized state, the five-year relative survival rate is 90 percent. But only 38 percent of colorectal cancers are discovered that quickly. If more people took screening seriously, experts say, that number would no doubt improve.

Toward that end, stricter guidelines on colorectal cancer screening were issued by the US Multi-Society Task Force on Colorectal Cancer in 2003.

The new recommendations suggest that before deciding how a person should be screened, a physician will first need to classify the person's level of risk, based on family history of the disease.

It is very crucial to know your risk, says Dr. Dennis Ahnen, a gastroenterologist and staff physician at the Denver VA Medical Center. Anyone with a family history or a personal history of colon cancer or polyps, which can precede cancer, is high risk, he says.

"If you have a single first-degree relative [such as a father or brother] with colon cancer at a young age, under 50, or more than one first-degree relative with colon cancer at any age, that is a strong family history," Dr. Ahnen says.

Those in a high-risk category should begin screening at age 40, or 10 years before the age at which the earliest colon cancer in the family occurred, Dr. Ahnen says.

Intermediate risk describes someone who has one family member with colon cancer that occurred after age 50, Dr. Ahnen says, although some experts say over age 60. For these individuals, screening should start at age 40.

People who have no family or personal history of cancer or polyps and no gastrointestinal diseases such as ulcerative colitis have an average risk, and they should start screening for cancer and polyps beginning at age 50.

Testing Options

Next is to decide, with your physician, the best options. Among them are colonoscopy, sigmoidoscopy, fecal occult blood testing, and double-contrast barium enema.

Colonoscopy involves the insertion of a long, flexible tube with a camera mounted on the end, up through the rectum and into the colon. The pictures taken by the camera are transmitted to a monitor.

A flexible tube is also inserted for sigmoidoscopy, but the viewing area is limited to a smaller part of the intestine - the sigmoid, or descending colon only.

Occult blood testing analyzes stool samples for blood, which can be a symptom of cancer.

Double-contrast barium enema is a radiological test in which a liquid is inserted into the rectum to better show the image of the GI tract on an X-ray.

Although the official guidelines offer an array of options, many experts say colonoscopy is the preferred test.

"Push as hard as you can for the best test, which is a colonoscopy," Dr. Johnson says.

In the future, "virtual" colonoscopies, which are less invasive than traditional colonoscopies, may become more common, Dr. Ahnen says. They use computer-assisted tomography to survey the colon from outside the body.

No matter which test you choose, experts say rectal bleeding, blood in the stool, a change in bowel habits, and cramping pain in the lower abdomen are all signs to get medical attention as soon as possible.

Always consult your physician for more information. 

Online Resources

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American Cancer Society

American College of Gastroenterology

Centers for Disease Control and Prevention (CDC)

Healthfinder, US Department of Health and Human Services (HHS)

National Cancer Institute

National Digestive Diseases Information Clearinghouse

National Institutes of Health (NIH)

March 2004

Colon Cancer Early Detection Helps Improve Outcome

Taking the Right Steps

Testing Options

Colorectal Screening Guidelines

What Is a Virtual Colonoscopy?

Online Resources

Colorectal Screening Guidelines

Current colorectal cancer screening guidelines from the American Cancer Society for early detection include:

Beginning at age 50, both men and women should follow one of the examination schedules below:

• fecal occult blood test (FOBT) every year

• flexible sigmoidoscopy (FSIG) every five years

• annual FOBT and FSIG every five years

• double-contrast barium enema every five years

• colonoscopy every 10 years

People with any of the following colorectal cancer risk factors should begin screening procedures at an earlier age and be screened more often:

• strong family history of colorectal cancer or adenomatous polyps in a first-degree relative, in a parent or sibling before the age of 60 or in two first-degree relatives of any age

• family with hereditary colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC)

• personal history of colorectal cancer or adenomatous polyps

• personal history of chronic inflammatory bowel disease

What Is a Virtual Colonoscopy?

Virtual colonoscopy compares favorably to the current "gold standard" of conventional colonoscopy, according to a report in the New England Journal of Medicine.

The procedure, using 3-D imaging technology, may eventually convince experts that virtual colonoscopy is a reliable screening tool.

"We have proved that virtual colonoscopy is a viable screening option," says lead researcher Dr. Perry J. Pickhardt, an associate professor of radiology at the University of Wisconsin Medical School.

Standard colonoscopy is a procedure that allows the physician to view the entire length of the large intestine, and can often help identify abnormal growths such as polyps, inflamed tissue, ulcers, and bleeding.

This test involves inserting a colonoscope, a long, flexible, lighted tube, in through the rectum up into the colon. The colonoscope allows the physician to see the lining of the colon, remove tissue for further examination, and possibly treat some problems that are discovered. Patients are usually sedated during the procedure.

The virtual colonoscopy, however, is completely noninvasive. In this procedure, usually a spiral CT scan is taken of the gastrointestinal area, and then a computer puts together an image of the person's colon for examination by a radiologist.

According to Dr. Douglas K. Rex, president of the American College of Gastroenterology, "Considering all available literature, conventional colonoscopy as currently performed remains the clear gold standard for the diagnosis of colorectal cancer and adenomas.

"Patients should be aware that in this study of virtual colonoscopy and in some others, they are more likely to experience significant discomfort with virtual colonoscopy than they are with conventional colonoscopy."

Dr. Rex adds, "Thus virtual colonoscopy is a diagnosis-only test, whereas conventional colonoscopy remains the only strategy that allows both diagnosis and treatment in a single session."

Always consult your physician for more information.