Through screening tests, colon cancer can be detected before symptoms develop. This is when the cancer is most curable.
Your doctor will perform a physical exam and press on your belly area. The physical exam rarely shows any problems, although the doctor may feel a lump (mass) in the abdomen. A rectal exam may reveal a mass in people with rectal cancer, but not colon cancer.
A fecal occult blood test (FOBT) may detect small amounts of blood in the stool. This may suggest colon cancer. A sigmoidoscopy, or more likely, a colonoscopy, will be done to evaluate the cause of blood in your stool.
Only a full colonoscopy can see the entire colon. This is the best screening test for colon cancer.
Blood tests may be done for those diagnosed with colorectal cancer, including:
If you are diagnosed with colorectal cancer, more tests will be done to see if the cancer has spread. This is called staging. CT or MRI scans of the abdomen, pelvic area, chest, or brain may be used to stage the cancer. Sometimes, PET scans are also used.
Stages of colon cancer are:
- Stage 0: Very early cancer on the innermost layer of the intestine
- Stage I: Cancer is in the inner layers of the colon
- Stage II: Cancer has spread through the muscle wall of the colon
- Stage III: Cancer has spread to the lymph nodes
- Stage IV: Cancer has spread to other organs outside the colon
Blood tests to detect tumor markers, such as carcinoembryonic antigen (CEA) may help the doctor follow you during and after treatment.