A colorectal cancer diagnosis is made when tests confirm the presence of malignant cells within the lower portion of the gastrointestinal tract. A variety of physical symptoms and risk factors can lead a physician to believe that colorectal cancer is a possibility. An examination of the lower gastrointestinal tract is typically called for when either the presence of warning signs or the age of a patient dictate it to be medically advisable. A test, typically a colonoscopy, harvests suspicious cells, which are sent to a laboratory for analysis. The diagnosis is made on the basis of these results.
Several symptoms are warning signs of colorectal cancer, including persistent bleeding, weight loss, intestinal pain. and a general feeling of weakness. Very narrow stools may also lead a doctor to consider a colorectal cancer diagnosis, as these can be caused by the presence of a tumor in the gastrointestinal tract. Certain medical conditions, including irritable bowel disease, increase the probability of a patient developing colorectal cancer. Some relatively rare hereditary traits make this type of cancer very likely. All of these symptoms can have other, less severe causes, however, and are never the sole basis for a colorectal cancer diagnosis.
A colonoscopy or equivalent procedure is normally used to screen for colorectal cancer. The procedure requires a probe with a small surgical instrument and a camera, which searches for abnormal growths, typically polyps, in the colon or large intestine. The probe retrieves samples of unusual cell growths and often removes growths entirely, as a prophylactic measure. Other tests are under development to perform this screening function, including some that use body scanning technology and others that use very precise blood testing to spot the presence of cancer. Regardless of type, testing of some sort is required for a definitive colorectal cancer diagnosis.
Once a sample has been collected during a colonoscopy or other screening procedure, it is sent to a laboratory for analysis. Laboratory testing can quickly determine whether a cell sample is comprised of benign but abnormal cells or of malignant cells. In the latter case, a colorectal cancer diagnosis is made.
If a careful testing schedule is followed, colorectal cancer can often be detected quite early. Routine screening in the absence of symptoms or risk factors typically begins at age 50. The presence of risk factors requires testing at a younger age, and the presence of potential symptoms is generally sufficient reason for a test at any age because an early colorectal cancer diagnosis can greatly improve patient outcomes.