Bowel cancer itself does not show up in blood tests.
However when you have a blood test done there is a chemical that can show up in your blood that can be a sign of colon cancer or bowel cancer.
The chemical that can show up in blood tests that can mean colon cancer or bowel cancer is the chemical called carcinoembryonic antigen, or CEA.
So if that chemical shows up in the blood tests then it can alert the doctor and yourself to possible colon cancer or bowel cancer.
To actually detect bowel cancer or colon cancer you need a colonoscopy to detect the bowel cancer or colon cancer.
If caught early enough and treated soon enough before it spreads the colon cancer can almost always be cured.
Be sure to get a colonoscopy by age 50 years old and continue getting colonoscopies every 10 years or sooner if you need too.