Study questions value of diet restrictions prior to colon cancer screening test

August 15, 2001

CHAPEL HILL - Avoidance of certain foods before taking a commonly recommended screening test for colon cancer may not be necessary, according to a report from the University of North Carolina at Chapel Hill.

The report appears Sept. 15 in Effective Clinical Practice, a publication of the American College of Physicians. The findings are based on an analysis of five randomized clinical trials published in the medical literature. The report points out that the proportion of people who test positive for fecal occult blood (traces of blood in the stool) is about the same whether or not they are advised to restrict their diet before obtaining the necessary stool samples.

Moreover, the report notes that dietary restrictions calling for avoidance of red meat, dark fish, and certain vegetables for several days before and during fecal occult blood testing (FOBT) might pose a barrier to screening.

This barrier, if lifted, may result in more people completing the test, the report suggests. "Our systematic review of randomized trials has shown that [test] completion rates do not differ when modest dietary restrictions are recommended, but more severe restrictions may reduce them," state the authors headed by Michael P. Pignone, MD, MPH, assistant professor of medicine at the UNC-CH School of Medicine.

Dietary restrictions for FOBT are meant to avoid getting erroneous test results, either false negative or false positive. Along with avoiding certain foods, current FOBT guidelines to doctors also recommend advising patients to abstain from aspirin and related anti-inflammatory drugs (NSAIDS) because of concern that they may also cause false positive results. Avoidance of vitamin C in amounts over 250 milligrams is recommended because it can cause false negative results.

Pignone, a member of UNC Lineberger Comprehensive Cancer Center, points out that screening for colorectal cancer with FOBT, despite its demonstrated effectiveness, remains underutilized. "Only 20 to 25 percent of U.S. adults older than 50 have had the test in the past year. In some studies, patients have reported difficulty in preparing for or performing the test," he said.

Pignone and his co-authors note that in one clinical trial in which an especially restrictive diet was used, 22 percent fewer people completed FOBT compared to those who did not receive dietary restrictions (51.3% versus 72.7%). In an accompanying editorial, Harvard Medical School professor Robert H. Fletcher, MD, MSC agreed with the report's conclusions. "I believe it is time to simplify dietary advice for FOBT testing, when possible," he wrote.

Fletcher, a former co-division chief of internal medicine at UNC-CH, added: "As for the diet itself, I recommend advising something similar to the following: 'Do not take any pain medications or more than a single multivitamin per day.'" He says such advice could make it easier for the occasional patient who finds FOBT dietary advice burdensome - at the cost of few, if any, erroneous test results.
-end-
Pignone's study co-authors were Marci Kramish Campbell, PhD, MPH, RD, associate professor of nutrition, School of Public Health and a member of the Lineberger Cancer Center; Carol Carr, MA, also with the center's Cancer Prevention and Control Project; and Christopher Phillips, MD, MPH, U.S. Force Medical Operations Agency, San Antonio, Texas.

Pignone's research is supported by an American Cancer Society Career Development Award.

Media note: Contact Dr. Pignone at 919-966-2276, pignone@med.unc.edu. School of Medicine contact: Leslie Lang, 919-843-9687, llang@med.unc.edu. Lineberger Cancer Center contact, Diane Shaw, 919-966-5905, dgs@med.unc.edu.

University of North Carolina Health Care

Related Colon Cancer Articles from Brightsurf:

New prognostic markers for colon cancer identified
The study recently published by MedUni Vienna and collaborative partners nominates ILSs as novel prognostic players orchestrating the pathobiology of metastatic colorectal cancer.

Turning colon cancer cells around
Using a modified natural substance along with current approaches could improve colon cancer treatment, according to findings by University of California, Irvine biologists.

Uncovering the pathway to colon cancer
The hidden world of genetic changes, or mutations, in healthy colon tissue has been uncovered by scientists at the Wellcome Sanger Institute and their collaborators.

Colon cancer growth reduced by exercise
Exercise may play a role in reducing the growth of colon cancer cells according to new research published in The Journal of Physiology.

Towards a better understanding of how colon cancer develops and progresses
Researchers from the University of Luxembourg have discovered a molecular mechanism that is responsible for the spread of cancer cells in the body and the development of metastases in patients with colon cancer.

New target protein for colon cancer identified
Researchers at Boston University School of Medicine (BUSM) have identified a new potential target protein (c-Cbl) they believe can help further the understanding of colon cancer and ultimately survival of patients with the disease.

Colon cancer -- Targeting tumor cell plasticity
Cell type switch helps colon cancer evade treatment, a study suggests.

A bacterial duo linked to colon cancer
Scientists have identified a combination of bacteria that appears to increase the risk of colon cancer.

New model could speed up colon cancer research
Using the CRISPR gene editing system, MIT researchers have shown they can generate colon tumors in mice that very closely resemble human colon tumors, an advance that should allow scientists to learn more about how the disease progresses and also help them test potential new drugs.

Are dialysis patients being over-screened for colon cancer?
Colonoscopies are being performed more often on healthier dialysis patients than on those with more limited life expectancies; however, overall, dialysis patients are being screened at a much higher rate relative to their life expectancy than their counterparts without kidney failure.

Read More: Colon Cancer News and Colon Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.