Colorectal cancer

Colorectal cancer occurs in the large intestine which is the last part of the digestive system. The large intestine consists of the colon and rectum. Colorectal cancer is the second leading cause of deaths from cancer in Canada. This type of cancer develops slowly and can be successfully treated if diagnosed early.

Causes

Certain factors and conditions can increase one's risk of developing colorectal cancer. Risk factors you cannot control:

• Being over age 50
• Having a history of polyps (growths in the mucous membranes)
• Having a family history (first-degree relative) of colorectal cancer
• Having a personal history of inflammatory bowel disease (Crohn's disease or ulcerative colitis)

Risk factors you can control:

• Intake of red meat
• Intake of processed meats (cold cuts, hot dogs, etc.)
• Alcohol use
• Low fruit and vegetable intake
• Lack of physical activity
• Smoking
• Overweight

Symptoms

In its early stages, colorectal cancer often has no symptoms. Some individuals may experience the following symptoms:

• Blood in the stools
• Changes in bowel habits (shape, frequency)
• Diarrhea or constipation
• Digestive problems
• Unexplained weight loss
• Fatigue
• Vomiting

Diagnosis

Colorectal screening is the best way to reduce mortality associated with this type of cancer. Screening is recommended every two years for those over 50 years of age. Individuals who present other risk factors over which they have no control have a higher risk of developing colorectal cancer, and should therefore start screening before the age of 50. Here are the main screening tests:

Fecal occult blood test
Certain blood vessels are easily damaged and bleed with the passage of feces. This blood cannot be seen with the naked eye. If the test results are positive and blood is detected, a colonoscopy is ordered to determine the cause of the bleeding.

Barium enema
A barium enema is a radiological examination of the rectum and entire colon using a barium preparation that is administered through the rectum. If any abnormality is detected, a colonoscopy is ordered. Now that colonoscopies are more accessible, barium enemas are not quite as common.

Colonoscopy
A colonoscopy involves the insertion of a flexible device through the anus to see inside the colon. Because a colonoscopy is an in-depth examination, it is the most effective way to detect colorectal cancer. If an anomaly is detected, a tissue sample can be taken for biopsy. Recently, a new technique known as virtual colonoscopy has gained attention and is currently being used. Since it uses X-ray imaging, it is less invasive than a traditional colonoscopy. If an abnormality is detected with a virtual colonoscopy, the patient will have to undergo a traditional colonoscopy.

Treatment

Depending on the size and location of the tumour, there are several treatment options. They can be used alone or in combination:

• Surgery - involves the removal of the affected portion of the colon or rectum.
• Radiation therapy - involves the use of a certain type of energy from X-rays to destroy cancer cells.
• Chemotherapy - an oral or injectable treatment that uses chemical agents to kill cancer cells.

Prevention

You can lower your risk of developing colorectal cancer by adopting healthy eating and lifestyle habits. Reducing your intake of red meat and processed meats, and eating more fruits and vegetables is highly recommended.

For more information:

• Colorectal Cancer Canada