By GINA KOLATA
The New York Times
An 18-year study of more than 46,000 people has found that a simple but little-used screening test may help prevent people from getting colon cancer.
The test, known as fecal occult blood screening, looks for traces of blood in a person’s stool, a possible sign of a cancer or benign polyps that can be precursors to cancer. When these polyps are removed, the cancer is prevented. In the study, the colon cancer rate was reduced by as much as 20 percent among people who had the test.
The federally financed study, described in toTday’s issue of The New England Journal of Medicine, was conducted by Dr. Jack Mandel, a vice president of Exponent, a Menlo Park, Calif., research company, and his colleagues.
Dr. Ernest Hawk, chief of the gastrointestinal cancer group at the National Cancer Institute’s division of cancer prevention, said that it was already known the test reduced the colon cancer death rate by allowing cancers to be detected in early stages. But this was the first evidence that those who use the test can avoid colon cancer in the first place.
Hawk said that people whose colon cancer was detected in its earliest stage had a five-year survival rate of 90 percent while those whose cancer is discovered in the latest stage had just an 8 percent survival rate.
"It’s like the ultimate stage shift," Hawk said of the new results. "Not only do you not get stage D cancer, you don’t get cancer at all."
Colon cancer kills 65,000 Americans a year, making it the leading cause of cancer deaths for men and women, after lung cancer. Besides the fecal blood test, doctors detect it by performing colonoscopies, in which a flexible scope is used to examine the entire colon, and sigmoidoscopies, in which a scope is used to examine the lower part of the colon, where most cancers occur. In addition, some doctors look for cancers with barium enemas.
But these tests are uncomfortable as well as being more expensive and elaborate than the fecal test. The fecal test is also the only one that has been shown in rigorous studies to reduce the colon cancer death rate, though doctors are convinced that the other tests have the same effect.
Colon cancers begin as harmless polyps which can be found and removed. Some researchers had long hoped that screening tests could prevent the disease. If so, they said, the testing would offer an unprecedented opportunity to attack a devastating and common cancer.
In the new study, there were 417 cases of the cancer among 15,532 people who were offered annual fecal blood tests; 435 cancer cases among 15,550 people offered the test every other year; and 507 cases among the 15,363 people who did not have the test — a 20 percent reduction in the cancer rate among those who were offered the screening test.
"What we had until now is evidence that early detection reduces the mortality from colon cancer," said Dr. Steven Woolf, a professor of family medicine at Virginia Commonwealth University who wrote an editorial accompanying the new study. "But early detection presumes the cancer already exists. This takes us to a new level."
The study began in 1975, nearly a decade after the fecal occult blood test was discovered but before anyone knew if it was effective in screening for colon cancer.
Their first result was published in 1993, showing that people who had the fecal blood test had a 33 percent reduction in their death rate from colon cancer. Two large European studies subsequently confirmed that result, Mandel said.
Medical experts say that it almost does not matter what test is chosen, as long as people are screened.
But, Mandel and others said, doctors should start urging their patients who are older than 50 to be screened using at least one of the tests.
"We have the means, we have the technology, to virtually eradicate this disease," Mandel said. "To me, that is quite exciting."
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