What are the symptoms of Colon Cancer?

Colorectal cancer often does not have any symptoms, but some symptoms associated with colorectal cancer include:
* A change in bowel habits such as diarrhea , constipation , or feeling that the bowel does not empty completely—lasting for more than a few days in people aged 50 and older
* Blood (either bright red or very dark) in the stool
* Stools that are narrower than usual
* Abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
* Unexplained weight loss
* Constant fatigue
These may also be caused by other, less serious health conditions. Anyone experiencing these symptoms should see a doctor.
Source: EmpowHER Medical Conditions: https://www.empowher.com/condition/colorectal-cancer/symptoms

It is recommended in the U.S. that all men and women, beginning at age 50 (with no family history of colon cancer) have the following colon cancer screenings performed:
* An annual occult blood test on spontaneously passedstool (at a minimum);
* A flexible sigmoidoscopy every 5 years; or,
* A complete colonoscopy every 10 years.
Source: http://www.asge.org/PatientInfoIndex.aspx?id=8074

There are different reasons why a virtual colonoscopy would be performed, versus a "regular" colonoscopy, and it depends on many factors that are individual to each patient. Here is some more information about why each test may/may not be performed (or, why both tests would be performed, to follow-up on a previous test):

"Virtual colonoscopy may be performed to:
* Follow-up on colon cancer or polyps
* Look for the cause of:
o Abdominal pain, changes in bowel movements, or weight loss
o Anemia due to low iron
o Blood in the stool or black, tarry stools
* Screen for cancer of the colon or rectum (should be done every 5 years)

Your doctor may want to do a conventional colonoscopy instead of a virtual colonoscopy. The reason is that virtual colonoscopy does not allow the doctor to remove tissue samples or polyps.

A regular colonoscopy may be done (on a different day) after a virtual colonoscopy if:
* No cause for bleeding or other symptoms were found. Virtual colonoscopy can miss some smaller problems in the colon.
* Problems that need a biopsy were seen on a virtual colonoscopy

Other times, a virtual colonoscopy is done if your doctor was not able to move the flexible tube all the way through the colon during a conventional colonoscopy."
Source: Medline Plus: http://www.nlm.nih.gov/medlineplus/ency/article/007253.htm