Dr. Nea Malila and colleagues at the Finnish Cancer Registry studied 106,000 people to test how sensitive screening was in identifying unrecognized disease.

A national screening program for colorectal cancer began in Finland in 2004 as a public health policy in 22 volunteer municipalities. It grew to include 161 municipalities by 2006.

Nationally, it was decided to split the 106,000 people into two groups -- a screening group that received fecal occult blood tests kits by mail, and a control group that received the routine health services available in the country. Anyone whose test indicated blood was contacted and advised to have a full colonoscopy.

The study, published in the British Medical Journal, finds 55 percent of those who tested positive for a fecal test developed cancer.

Researchers concluded that the sensitivity of the Finnish program was "adequate if relatively low."