Having a blood test done cannot tell if you have colon cancer although the blood test can detect other things that can clue the doctor in on you probably having colon cancer.
To test and find out if you have colon cancer a colonoscopy will need to be performed where they put a camera up your anus to check for colon cancer.
If caught early enough then the colon cancer can usually be cured.
The doctor will use A colonoscope which is a four-foot long, flexible tube about the thickness of your finger with a camera and a source of light at its tip.
The colonoscope allows the doctor to see inside your anus to check for the colon cancer.