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 only about a third of Americans older than 50 have ever been tested, and Mandel said it is estimated that at most a quarter of Americans older than 50 ever had a fecal occult blood test. He said that one reason for the dismal screening record is that doctors have tended not to recommend the test. The fecal test, in particular, was mired in controversy because it was marketed for about 30 years before there was compelling evidence that it reduced the colon cancer death rate, he said.
Colon cancers begin as harmless polyps that 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. 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.