The development of colorectal cancer from a polyp may take between five to ten years and there may be no symptoms at all. Many symptoms are similar to those of irritable bowel syndrome and this can sometimes cause difficulty in making a diagnosis. A prolonged change in bowel habit lasting more than two or three months should always be investigated.
The most common symptoms are bleeding from the bowel, a change in bowel habit, such as unusual episodes of diarrhea or constipation, or an increase in the amount of mucus in the stool.
Colorectal cancer can enlarge so that it partially or completely blocks the bowel which leads to abdominal pain, constipation and bloating. Sometimes tiny amounts of bleeding may go unnoticed, but may result in the development of anemia, which may cause tiredness and a decreased ability to work and exercise.
What is my risk?
There are three levels of risk for colorectal cancer; average, increased and high.
Average risk is for someone over age 50, with no family history of colorectal cancer and no family history of inflammatory bowel disease.
Increased risk is for someone with a personal history of an Adenoma polyp, prior colorectal cancer, inflammatory bowel disease or someone in the family with colorectal cancer.
High risk is someone with Lynch Syndrome, polyposis syndromes or someone in the family with colorectal cancer.
What tests confirm a diagnosis of colorectal cancer?
Colonoscopy: This test requires laxatives to clear out the bowel. A flexible telescope is passed through the anus into the rectum. The tube is long enough to examine the entire large bowel. The procedure is a little uncomfortable and most patients are offered an injection of pain reliever to ease any discomfort or sleep. If the colonoscopy test is normal the National Comprehensive Cancer Network (NCCN) guidelines recommends one every 10 years, but consult with your health care provider for your personal recommendation.
CT scanning (Colonography or Virtual Colonoscopy): This is a relative new X-ray procedure and has the advantage, (which many people appreciate) of not involving a tube being passed through the anus. At this time it is not yet as reliable as colonoscopy but its quality is steadily improving and an increase in usage is likely.
Both virtual colonoscopy and colonoscopy have the advantage that a small sample or biopsy can be taken to look at under the microscope. The above tests are used in slightly different situations depending upon the symptoms that patients may have and the availability of the needed equipment.