Early Colorectal Cancer Screening Saves Lives

Nile Cruise Dancer (Dr. Noorali Bharwani)
Nile Cruise Dancer (Dr. Noorali Bharwani)

Colorectal cancer is the second most commonly diagnosed cancer in Canada and the second leading cause of cancer death. First being lung cancer.

It is estimated about one in 13 men and one in 16 women will be diagnosed with colorectal cancer during their lifetime. Seventy per cent of cancers are in the colon and 30 per cent are in the rectum.

Over the years we have been diagnosing colorectal cancer at an earlier stage thanks to public awareness and the variety of screening tests available to the public. Cancer diagnosed early has about 90 per cent survival rate. Cancer diagnosed in advanced stage has about 10 per cent survival rate.

There are many ways to get the general public involved in the screening programs. The programs can be adjusted to an individual’s needs and fears. Screening tests are purely for people who have no bowel symptoms or family history of colorectal cancer or polyps. For them screening should begin at age 50 and we have a variety of tests to choose from.

Colonoscopy is the most accurate test for detecting colorectal cancer, proven to detect the disease early and save lives. But even a very good test can be done too often, according to experts at Choosing Wisely Canada (CWC). CWC is the national voice for reducing unnecessary tests and treatments in health care. Having a colonoscopy more than once every five or ten years usually isn’t necessary unless there are clear indications. Routine checks usually aren’t needed after age 75.

If a screening colonoscopy does not find adenomas (pre-malignant benign tumours) or cancer and you don’t have risk factors, the next test should be in ten years. If one or two small low-risk adenomas (polyps) are removed, the exam should be repeated in five to ten years.

Some individuals, who are at a low or average risk of colorectal cancer would prefer to go for an alternative test. For whatever reasons, some people do not like the idea of getting a screening colonoscopy. Here are some other choices, though not as good as colonoscopy.

Virtual colonoscopy (CT colonography): During a virtual colonoscopy, a CT scan produces cross-sectional images of the abdominal organs, allowing the doctor to detect changes or abnormalities in the colon and rectum. To help create clear images, a small tube (catheter) is placed inside your rectum to fill your colon with air or carbon dioxide. Virtual colonoscopy takes about 10 minutes and is generally repeated every five years.

Fecal occult blood test or fecal immunochemical test: These are lab tests used to check stool samples for hidden (occult) blood. The tests usually are repeated annually.

Flexible sigmoidoscopy: During flexible sigmoidoscopy, a thin, flexible tube is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the rectum and most of the lower part of the colon (sigmoid colon). A flexible sigmoidoscopy test takes about 20 minutes and is generally repeated every 5 years.

Stool DNA test: The stool DNA test uses a sample of your stool to look for DNA changes in cells that might indicate the presence of colon cancer or precancerous conditions. The stool DNA test also looks for signs of blood in your stool.

If any of the above test is positive then you must have a colonoscopy to confirm the findings and manage the problem.

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Are we doing too many colonoscopies? The new guidelines are here.

Dr. Noorali Bharwani demonstrating flexible sigmoidoscopy.
Dr. Noorali Bharwani demonstrating flexible sigmoidoscopy.

First, let us face the facts. Colorectal cancer is the third most commonly diagnosed cancer in Canada. It is the second leading cause of cancer death in men and the third in women. The lifetime probabilities of dying from colorectal cancer among men and women are three to four per cent.

What’s the best way to prevent colon and rectal cancer?

We have been doing colonoscopies just over 50 years. The technology is changing almost every year. The service is now available almost everywhere. There are more doctors doing colonoscopy. And people are getting the procedure done more often. The indications of doing the procedure are increasing everyday. The saying goes, “If you haven’t had a colonoscopy then you need one. If have had one then you need another one!” Is that the way to go?

Last time the guidelines for colonoscopy were updated was 2001. Now, in 2016, we have new guidelines from the Canadian Task Force on Preventive Health Care. The new guidelines state there is not enough evidence to justify colonoscopies as routine screening for colorectal cancer. Instead, patients should undergo fecal occult blood testing every two years, or flexible sigmoidoscopy every 10 years. Flexible sigmoidoscopy is a procedure in which a scope is inserted in the lower portion of the colon and rectum rather than the entire tract. I used to provide that service in my office.

It is sad to note that currently no provincial screening program includes flexible sigmoidoscopy.

It is important to remember that the guidelines apply to adults aged 50 to 74, who are asymptomatic and at low risk for colorectal cancer, meaning they have no prior history of the disease, no family history, no symptoms such as blood in the stool, or genetic predisposition. If they have any of these risk factors then they need a colonoscopy – full examination of the colon and rectum.

The task force hopes that ultimately, most Canadians will likely be screened using fecal occult blood tests, which look for microscopic specks of blood in the stool that could be a sign of cancer. If that is positive then a colonoscopy is indicated. If a flexible sigmoidoscopy (a 60-cm scope which examines the rectum and left colon) is positive for any abnormal findings then the person needs a colonoscopy.

To spread this message, we have to educate the public about the risk of the disease and the safety and importance of screening. Adults 75 and over should not be ignored. If they are in good health then they should discuss with their doctor and get into the screening program.

Colonoscopy is a great test but because waiting lists are long and the potential for side effects such as bleeding or intestinal perforation are greater than they are for other tests, the guidelines recommend against using colonoscopies as a routine screening tool in asymptomatic low-risk adult.

The old guidelines (2001) recommended annual or biennial faecal occult blood test (FOBT) and flexible sigmoidoscopy every five years in asymptomatic people older than 50 years. The guideline did not recommend whether these screening modalities should be used alone or in combination or whether to include or exclude colonoscopy as an initial screening test for colorectal cancer. And provincial screening programs do not include flexible sigmoidoscopy as one of their screening options. This should change.

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Rectal Bleeding and Hemorrhoids

“Hello doctor, I am Maggie, Susan’s mother. I have been passing blood in my stool. Do you think it is hemorrhoids? Dave and Susan think it could be cancer.”

Maggie is sixty seven. She has been bleeding rectally for the last two years. Over-the-counter medications for local application have not helped. Has she got colon or rectal (colorectal) cancer?

Colorectal cancer affects men and women equally. It is the fourth most common cancer site. It is the second leading cause of cancer deaths in men and women combined ( A Snapshot of Cancer in Alberta-1996).

Do we know what causes colorectal cancer? No. If we did then prevention and cure would be easy. But we do know the risk factors.

Like breast cancer, age is a significant factor. Before the age of forty, the incidence is pretty low. But by the age of fifty, the risk begins to increase dramatically.

What about lifestyle and nutrition?

Studies have shown that death from colorectal cancer can decrease with increased intake of fiber, fruits, and vegetables. Decrease in fat intake also helps.

Increased physical activity, aspirin and avoiding cigarette smoking may be beneficial.

Heredity and genetics is now recognized as a risk factor for this disease. Studies have shown that if there is a family history of colorectal cancer in a parent or a sibling , then a person’s lifetime risk of colorectal cancer jumps from 1.8 fold to 8.0 fold.

Previous history of colorectal cancer or polyps, inflammatory bowel disease and exposure to radiation are other significant risk factors.

With this information in the back of my mind, I take a full history from Maggie and do a thorough physical examination.

The physical examination is normal. A digital rectal examination reveals no suspicious lumps. A proctosigmoidoscopy ( a hollow tube with a light at one end to examine the rectum) shows internal hemorrhoids but no lumps to suggest a new growth of tissue.

Although Maggie has internal hemorrhoids, there are about fifty percent chances that the blood could be coming from higher up in the colon. This may or may not be due to cancer. But she requires further investigation like colonoscopy.

Examination of the entire colon by colonoscopy (a thin, flexible tube made of fibers that transmit light) is the most important test for looking, taking biopsies and when possible, removing growths. Maggie agrees to have the test done as soon as possible.

Maggie has to take laxatives to clean the colon completely of waste products the day before the procedure. The test is done at the hospital as day surgery and under sedation.

A polyp (new growth of tissue) is discovered and removed during colonoscopy. This is sent to the lab for testing to see if it is benign or malignant. In the meantime, she makes an appointment to see me in the office for the results.

Susan accompanies Maggie to make sure her Mom understands the results and its implications. Susan also wants to know how the findings will affect her (Susan’s) health in the future.

“Maggie, I have good news for you. The polyp is benign in nature but it’s a type which can come back and turn into cancer if not picked up early and removed.”

“Dr. B, thank you for the good news. Now I have the same old question for you. How can my mom and I stay one step ahead of the game?” Susan asks with a sense of relief.

Eat less fat. Eat more fiber-containing foods. Have a digital rectal examination and annual stool test for hidden blood and colonoscopy every 3 to 5 years. Report to your doctor earlier if there is any change in bowel habit.

Maggie and Susan are happy that this is all over. As they leave the examination room, I overheard Maggie say to Susan, “I hope now you will listen to your mother and start eating bran flakes cereal in the morning!”

(This series of articles explore the health problems of Dave and his family. They are composite characters of a typical family with health problems)

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