Are occult blood tests for colon cancer effective?

Not optimal: Occult blood in stool (fobt) are helpful in detecting colon cancer and their use improves outcomes. However, fobt by itself is not a treatment therefore it is not possible to comment on its effectiveness. Colonoscopy is a much better screening test.

Yes: Yes. Testing occult blood in the stool is very effective simple inexpensive test for screening for colon cancer, screening colonoscopy is most accurate test for colon cancer.

Guaiacs-: Are actually tests of thin films of stool to discern if there is hidden blood beneath visiblity, so-called "occult blood". It is a great screen, that if positive leads to a closer, less comfortable, more expensive test: colonoscopy. After 50, you get one per decade without occult blood in stool!