But this was the first evidence that those who use the test can avoid colon cancer in the first place. Dr. 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, stage D, had an 8 percent survival rate. 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 second- biggest 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.
Some doctors also look for cancers with barium enemas.
But these tests are uncomfortable, more expensive and more 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. Few Americans have any colon cancer screening. The American Cancer Society estimates that about a third of Americans older than 50 have been tested, and Dr. Mandel said that at most a quarter of Americans older than 50 have ever had a fecal blood test. But early detection presumes the cancer already exists.