SCREENING SAVES LIVES
In the majority of cases, colorectal cancer is preventable and yet, thousands of people are diagnosed with advanced stage colorectal cancer each year in Canada. If, however, the cancer is detected early through screening, it may be highly treatable and potentially curable.
The majority of colorectal cancers begin as benign growths in the lining of the large intestine wall called adenomatous polyps. Over the years (between 5 and 10 years), these polyps grow in size and number, thereby increasing the risk that the cells in the polyps will become cancerous, invade the wall, and move on to other organs. Approximately two-thirds of these cancers are found in the large intestine and one third in the rectum. Early identification and removal of these growths will prevent colorectal cancer from developing in the first place.
Clearly, being screened as part of a regular physical exam has the potential to save lives. Patients at a higher risk of developing colorectal cancer and those experiencing related symptoms should not delay talking to their doctor about appropriate screening and diagnosis options.
DID YOU KNOW?
Most colorectal cancer deaths could be avoided if everyone aged 50 years and older underwent regular screening tests.
It is a common misconception that colorectal cancer is a disease that primarily strikes men. Colorectal cancer affects men and women almost equally.
More than 90% of the time, colorectal cancer can be effectively treated when diagnosed at its earliest stage through colonoscopy.
TYPES OF SCREENING TESTS
According to the Canadian Cancer Society, screening or testing should be performed while the patient is feeling well to identify any abnormalities early before signs and symptoms of disease occur.
The Canadian Task Force on Preventive Health Care (CTFPHC) has issued the following screening recommendations for adults aged 50 – 74 years who are not at high risk for colorectal cancer. These recommendations do not apply to those with previous colorectal cancer/polyps, Inflammatory Bowel Disease, signs/symptoms of colorectal cancer, history of colorectal cancer in one or more first-degree relatives or adults with hereditary syndromes related to colorectal cancer (e.g. Lynch Syndrome).
There are several tests used to screen for colorectal cancer and polyps:
- Guaiac Fecal Occult Blood Test (gFOBT): A test in which a stool sample is collected and returned to the doctor or lab to test for occult (hidden) blood.
- Fecal Immunochemical Test (FIT or iFOBT): Uses antibodies to detect human hemoglobin protein in stool. Much like the gFOBT, this test detects the presence of blood in the stool and may be more accurate.
- Flexible Sigmoidoscopy: A thin, flexible, lit tube with a small video camera located at its end is inserted through the anus in order to view the inside of the lower part of the colon and rectum (usually around the lower two feet) for polyps and cancer-related growths.
- Colonoscopy: A thin, flexible, lit tube with a small video camera located at its end is inserted through the anus in order to view the inside of the entire colon and rectum for polyps and cancers.
- CT Colonography (Virtual Colonoscopy): A less invasive test using special x-ray equipment to produce pictures of the colon and rectum.
- Stool DNA Test or Fecal DNA Testing: Much like the FOBT and FIT, the stool DNA test screens a stool sample but instead of looking for blood, it looks for DNA that may signal the presence of cancer or polyps in the colon.
Using artificial intelligence solutions to facilitate better detection of polyps in CRC screening
In this video, Dr. Doug Rex shows the artificial intelligence program ai4gi in action, helping physicians find malignant polyps quicker and with higher accuracy for faster diagnosis and treatment.
SCREENING GUIDELINES IN CANADA
While various organizations, including the CCC, work to increase the number of individuals getting screened appropriately and to promote high quality cancer screening services across the country, each province and territory in Canada is responsible for establishing its own screening guidelines for colorectal cancer. These guidelines pertain to individuals in the following three categories: asymptomatic, average-risk and high-risk.
A list of colorectal cancer screening resources for each province and territory can be found here.
In addition, The Canadian Task Force on Preventive Health Care (CTFPHC), established by the Public Health Agency of Canada, published national clinical practice guideline recommendations for colorectal cancer screening in 2016. They recommend that individuals at average risk, aged 50-74, screen for colorectal cancer with an FOBT [either fecal test guaiac (FTg) or FIT] every two years or a flexible sigmoidoscopy every 10 years.
Additionally, the Canadian Task Force on Preventive Health Care does not recommend the following:
- Screening individuals aged 75 and over for colorectal cancer
- Using colonoscopy as a primary screening test for colorectal cancer