'Beeting' the Colon Cancer Test

What you eat won't affect fecal results, says study

TUESDAY, Aug. 21, 2001 (HealthDayNews) -- You can have meat and tomatoes and still take that colon cancer test, say doctors at the University of North Carolina (UNC).

Previously doctors thought eating certain foods may have made you test positive for colon cancer when you really didn't have it. A review of studies of about 10,000 adults found no differences in positive findings among those who followed dietary restrictions before a fecal colon cancer test and those who did not. A positive finding usually leads to more elaborate and expensive tests.

"We can reasonably assume that false positives aren't increased by eliminating the food restrictions," says Dr. Michael Pignone, a medical professor at UNC at Chapel Hill and lead author of a report to be published in the Sept. 15 issue of the journal Effective Clinical Practice.

In fact, Pignone says the only restriction should be to avoid taking more than 250 milligrams of vitamin C for three days before the test. Too much vitamin C can make the test finding negative even if you do have cancer, he says.

"The dietary restrictions create a small barrier, which may be enough for some people not to take the test. If the restrictions don't work, why do them?" he says.

Mt. Kisco gastroenterologist Elie Abemayor says, "I don't think the food restrictions make a difference. People just don't like to do the test."

When he prescribes the test, Abemayor says he tells patients to avoid aspirin and Advil because those drugs can irritate or cause bleeding in the colon. He also urges patients to avoid raw meat, which he says can cloud the results. "But I don't care about the food -- spinach, tomatoes, etc."

He says the problem is that the food restrictions included on the test instructions can be confusing.

The fecal test is designed to detect blood in the stool, which could be a sign of colon cancer. The test can be done at home and then mailed to the doctor for analysis. The American Cancer Society (ACS) recommends that every person over age 50 have a fecal occult blood test (FOBT) and repeat it annually, along with other doctor-recommended tests for early detection of colon cancer. The disease is highly treatable if caught early.

Last year 93,800 news cases of colon cancer and 47,700 deaths were reported. The ACS sys the incidence of the disease has declined greatly since 1992, probably due to increased screening and the removal of polyps that could lead to cancer.

However, Pignone says 75 percent of the population over 50 did not have a colon-cancer test last year.

"Even with Katie Couric, we haven't gotten the message out there [about the importance of early detection]," Pignone says. NBC ''Today'' anchor Katie Couric has crusaded against colon cancer since it killed her husband three years ago.

Pignone and his colleagues analyzed five studies of the impact of food restrictions on fecal testing and found food intake made no difference in test results. Further, when people were asked to follow especially strict dietary restrictions, compliance declined.

He says, "In one study there were 25 things restricted, like red meat, cantaloupe, beets, radishes and tomatoes," and about 22 percent fewer people finished the fecal test compared with those who received no restrictions (51.3 percent compliance compared with 72.7 percent compliance).

Pignone says food restrictions probably were attached to the fecal test for misguided reasons. One of the two ways to analyze FOBT results includes a drop of distilled water, called rehydrated testing. Another way is without water, called unrehydrated. Water added to fecal matter makes it easier to see blood in the stool, but also creates more false-positive readings, he says.

He says, "Most tests in this country are now unrehydrated, and [the restrictions] may be a carryover from the other testing."

What To Do

For information about risks and prevention of colon and other cancers, visit the ACS. To learn about the different tests for colon cancer, go to Veterans Affairs Medical Center, San Francisco.

If you need to be convinced about the importance of the test, here's Katie Couric's testimony before Congress.

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