[MadRiverTurtle]

By NICHOLAS BAKALAR
Published: January 30, 2009

The quickest and cheapest screening test for colorectal cancer is far from perfect, and a new study has shown that there are at least a half-dozen equally simple tests, not widely used in the United States, that are more reliable.

Although many consider colonoscopy to be the gold standard of colon cancer screening, the procedure has some drawbacks, so a simple and inexpensive screening test that detects precancerous lesions is an important tool.

Colonoscopy is expensive, has risks for serious complications and requires so much time, equipment and expertise that its wide use for screening is impractical, if not impossible. Recent research also shows that it may miss far more cancers than previously thought.

The most widely used quick test is a fecal occult blood test in which a small amount of stool is smeared onto a piece of cardboard impregnated with guaiac, a substance that quickly turns blue when exposed to blood. Because precancerous lesions can bleed periodically, a positive test suggests their presence. But the test is not specific for human blood, and consuming certain foods, medicines or vitamin supplements can produce false readings.

In the new study, German researchers tested guaiac against six new screens, called fecal immunochemical tests, which use antibodies to detect human hemoglobin and which cannot be falsified by diet or medicine. The researchers screened 1,319 men and women before their scheduled colonoscopies, then compared the results with results of the colonoscopies.

All the immunochemical tests were more accurate than the guaiac screen. The two most accurate detected more than 25 percent of those with benign lesions larger than one centimeter, the ones most likely to become cancerous. They also correctly identified, respectively, 93 and 97 percent of those who had no lesions. The guaiac test correctly classified 9.7 percent of those who had lesions, and 95.9 percent of those who had none.

“It’s important not to consider all fecal occult blood tests as being equal,” said Ulrike Haug, a coauthor of the study and an epidemiologist at the German Cancer Research Center in Heidelberg. “Quality assurance is as important for diagnostic tests as it is for drugs.”

The study’s subjects were selected from a general population, and those who interpreted the screening tests did not know the results of the colonoscopies, factors that give the study considerable strength. It appears Tuesday in The Annals of Internal Medicine.

“What this study shows,” said Dr. David Lieberman, a gastroenterologist at Oregon Health and Science University, “is that the tests can detect some patients who have cancer precursor lesions, but the best of them could only identify about one out of four with the most advanced lesions.”

But Dr. James E. Allison, an emeritus professor of medicine at the University of California, San Francisco, said that “the fecal occult blood test is the only one proven in randomized trials to actually decrease mortality from colorectal cancer.”

Neither Dr. Lieberman nor Dr. Allison was involved in the study.

Dr. Lieberman said that patients and their doctors had to decide on the goal of screening. “If your goal is not just to detect cancer but to prevent it, then with a colonoscopy you will find polyps, remove them, and may prevent cancer from developing at all,” he said. “There is good evidence that detection and removal of polyps does prevent some cancers.”

Dr. Allison, on the other hand, said that “the results of this study and others clearly show that the use of these tests not only detects cancer but also prevents it.”

“Furthermore,” he added, “the repeated use of this test allows for a higher rate of detection of advanced adenomas over time, and before cancer develops.”

Experts disagree about when to screen with fecal blood testing and when to use colonoscopy. But this study shows that there are better fecal blood tests than the one most often used in the United States.

“The new tests have been used in other countries since 1996, and shown to work,” Dr. Allison said. “Why are we still talking about them instead of using them?”

http://www.nytimes.com/2009/02/03/he...tml?ref=health

[tomo7]

My doc just recently told me that I was checked for colon cancer (among other things) through a simple blood test.
He said that my result reading # should be under a (4) to be safe & Mine was a (.04) so he said I was very safe & put my next colon cancer check of till I reach 50. ( I'm 46 now).
But that just seems too simple some how. Not that I'm ready for something else:slaugh: