THURSDAY, Nov. 20 (HealthDay News) -- Colorectal cancer screening detects 40 percent of cancers and should be carefully planned to be more effective, say Finnish Cancer Registry researchers.

They studied 106,000 people, aged 60 to 64, to determine how sensitive Finland's colorectal cancer screening program was in identifying unrecognized disease. Half the people were assigned to a screening group and received fecal occult blood test kits by mail (the test detects small traces of blood in feces that may indicate early-stage disease), while the other half were assigned to a control group that received routine health services.

People whose fecal occult blood test indicated the presence of blood were contacted to undergo a colonoscopy. The sensitivity (accuracy) of the test was 55 percent when considering cancers that developed after positive tests, the study found. Sensitivity from screening episodes was 51 percent, and sensitivity was 38 percent for the national screening program.

About 40 percent of colorectal cancers were detected through the colorectal cancer screening program.

"The sensitivity of the Finnish screening program for colorectal cancer at the first round was adequate even if relatively low. Program sensitivity in Finland was sufficient to justify continuation of the program," the researchers wrote.

The study was published online in BMJ.

In addition to sensitivity, there are other important factors that should be considered when evaluating a cancer screening program, Joan Austoker and Paul Hewitson, of the University of Oxford in the United Kingdom, wrote in an accompanying editorial.

Colorectal cancer is the second leading cause of cancer deaths in Europe and in the United States.

More information

The U.S. National Cancer Institute has more about colorectal cancer screening.