Possible signs of colon cancer include a change in bowel habits or blood in the stool.

These and other symptoms may be caused by colon cancer. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• A change in bowel habits.
• Blood (either bright red or very dark) in the stool.
• Diarrhea, constipation, or feeling that the bowel does not empty completely.
• Stools that are narrower than usual.
• Frequent gas pains, bloating, fullness, or cramps.
• Weight loss for no known reason.
• Feeling very tired.
• Vomiting.

Tests that examine the rectum, rectal tissue, and blood are used to detect (find) and diagnose colon cancer.

The following tests and procedures may be used:

• Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.
• Fecal occult blood test: A test to check stool (solid waste) for blood that can only be seen with a microscope. Small samples of stool are placed on special cards and returned to the doctor or laboratory for testing.

Fecal Occult Blood Test (FOBT) kit to check for blood in stool.