Early diagnosis of colorectal cancer by faecal occult blood detection - the Goteborg trial

Study hypothesis: By detection of early stages of colorectal tumours in the "healthy population", mortality from colorectal cancer is reduced.
Underlying this hypothesis is a further hypothesis that colorectal tumours develop over a time sequence, probably several years, from benign adenomas through localised cancer to cancer with spread growth, and that tumours in this sequence of development can be detected before they give symptoms observed by the individual.
Primary outcome(s): Mortality in colorectal cancer.
Time points were: after invitation, after screening participation, after work-up of positive screen test and after treatment for patients with positive work-up.