What is Colorectal Cancer?
Colorectal cancer begins when healthy cells in the lining of the colon or rectum change and grow out of control, forming a mass called a tumour. A tumour can be cancerous or benign. A cancerous tumour is malignant, meaning it can grow and spread to other parts of the body. A benign tumour means a tumour can grow but will not spread. These changes usually take years to develop. Both genetic and environmental factors can cause the changes. However, when a person has an uncommon inherited syndrome changes can occur within months to years.
What is Colorectal Polyps?
Colorectal cancer most often begins as a polyp, a noncancerous growth that may develop on the inner wall of the colon or rectum as people get older. If not treated or removed, a polyp can become a potentially life-threatening cancer. Recognizing and removing precancerous polyps can prevent colorectal cancer.
There are several forms of polyps. Adenomatous polyps, or adenomas, are growths that may become cancerous. They can be found with a colonoscopy. Polyps are most easily found during colonoscopy because they usually bulge into the colon, forming a mound on the wall of the colon that can be found by the doctor.
About 10% of colon polyps are flat and hard to find with a colonoscopy unless a dye is used to highlight them. These flat polyps have a high risk of becoming cancerous, regardless of their size.
What are the Symptoms?
Colorectal cancer is often a silent disease, developing with no symptoms at all. When symptoms do occur they may include the following:
- Blood in or on the stool
- Change in bowel habits
- Stools that are narrower than usual
- General stomach discomfort (bloating, fullness, and/or cramps)
- Diarrhea, constipation, or feeling that the bowel does not empty completely
- Frequent gas pains
- Weight loss for no apparent reason
- Rectal bleeding
- Constant tiredness, or new fatigue during activity that was previously tolerated
How Do I Get Checked for Colorectal Cancer?
Current screening methods include
- Fecal occult blood testing (a simple chemical test that can detect hidden blood in the stool)
- Flexible sigmoidoscopy (a visual examination of the rectum and lower portion of the colon, performed in a doctor’s office)
- Double contrast barium enema (barium x-ray)
- Colonoscopy (a visual examination of the entire colon)
- Digital rectal exam
Virtual colonoscopy, or CT colonography, is also being used in some specific situations but is not recommended as a mainstream screening test as of this time. Colorectal cancer screening, including colonoscopies, costs are covered by Medicare and many commercial health plans.