Why You Should Get Screened for Colorectal Cancer Early

Oscar Wilde once famously said, “With age comes wisdom, but sometimes age comes alone”.

While that may be true for those who believe that being older makes you wiser by default (ah, the irony), the same cannot be said of our health. ‘With age comes the aches and pains’ may be a more truthful statement to make.

Aside from typical aging ailments such as osteoporosis, cataract, hearing loss and more, the risk of colorectal cancer among others also increases with age. It isn’t necessarily an ‘old-person’ disease — the incidence of colorectal cancer in young adults is on the upward trend — but the chance of getting colorectal cancer usually begins to climb from age 40, and sharply increases after 50. This is why doctors often recommend routine screening for colorectal cancer past a certain age.

Cancer screening may differ depending on what exactly you’re checking for, but its goal remains the same: to detect cancer before the symptoms appear.

While the risks increase with age, the chances of successful treatment and complete recovery from colorectal cancer also improve if the tumor is localized in the bowel when detected, i.e. the cancer is still in its early stages and hasn’t spread to other parts of the body. Patients with localized colorectal cancers have a survival rate of 91%, while cancers that have spread to a nearby region result in a survival rate of 72%. This changes drastically when the cancer has progressed aggressively and spread to distant organs, with a survival rate of just 14%.

You don’t have to wait till you’re 40 to start screening for colorectal cancer, though. Many of the early colorectal cancer symptoms are easily overlooked because they are often innocuous and easy to pass off as caused by something else. Experiencing a sustained change in bowel habits with no clear cause may warrant a screening session to ascertain if something more serious is at play.

A variety of colorectal cancer screening tests are available These range from easy, self-administered stool-based tests to the more invasive scope-based tests that require insertion of a tube into the body to visualize the colon and rectum. These screening tools also offer different levels of accuracy and functionality and are often used in a complementary fashion.

Stool-based tests

As the name suggests, stool-based tests require samples taken from bowel movement to check for any potential signs of colorectal cancer. While these tests are generally non-invasive and can be conducted in the privacy of your own home without supervision, a follow-up colonoscopy is required if the test results turn out positive.

A guaiac-based fecal occult blood test (gFOBT) makes use of a chemical known as guaiac to detect the presence of occult, or hidden blood in the stool.

Where polyps are present, the connected blood vessels tend to be more fragile and can burst while digested food is being passed through the large intestine. The blood from the polyps is also passed out in the stool, resulting in a positive gFOBT test.

A gFOBT typically requires samples of stool from three separate bowel movements and has several dietary and drug restrictions prior to collecting the sample. NSAIDs, red meat and a vitamin C intake exceeding 250 mg a day should be avoided prior to a gFOBT test.

Frequency: Once a year

The fecal immunochemical test (FIT) is similar to the gFOBT in many ways, except that instead of using guaiac to test for occult blood, it utilizes antibodies for detection. The test can also be self-administered at home by following instructions on the test kit and does not impose any dietary restrictions prior to conducting the test.

Frequency: Once a year

The stool DNA test — sometimes called the FIT-DNA test — combines FIT with a test that detects abnormal DNA in the blood.

Polyps typically arise as a result of DNA mutations, and these cells are sometimes passed out in the stool. Whereas occult blood stool tests like gFOBT and FIT may be indicative of non-cancerous problems such as ulcers or hemorrhoids, the presence of both occult blood and altered DNA in the stool may be an indication of cancerous polyps in the colon.

The FIT-DNA test requires only one stool sample, and does not require a restricted diet prior to the test.

Frequency: Once every three years

Visual examinations

Unlike stool-based tests that rely on detecting the presence of certain compounds in the stool, visual examinations seek to detect the presence of cancer by observing the physical appearance of the colon and rectum.

In a colonoscopy and flexible sigmoidoscopy, a scope made up of a long, thin, flexible tube with an attached camera is inserted through the anus into the rectum and colon, and images of the intestinal lumen are visualized on a screen. These screening tests require the patient to have the bowels emptied beforehand. Similarly, rigid proctoscopy examines the inner lining of the rectum and anus for tumors and polyps, as well as other issues such as inflammation, hemorrhoids and bleeding. While the proctoscope shares many similarities with the colonoscope and sigmoidoscope, the tube is shorter and more rigid.

Before commencing the test, you will be asked to lie on your left side with your knees pulled up towards your chest, similar to a fetal position. The lubricated scope is inserted into the anus, and pumps air into the rectum and anus to provide an unobstructed view of the inner lining. While this may cause some discomfort, it should not be painful. Sedation is not a necessity for these procedures, but is an available option.

If polyps are found, a small instrument can be inserted through the scope to remove the polyp or retrieve a sample for a biopsy. Small amounts of blood may be found in the stool for a few days after the test, and while serious bleeding resulting from injury to the colon and rectum may occur, it is not common.

While the procedures for colonoscopy and sigmoidoscopy are similar, there are some key differences. As the name suggests, a sigmoidoscopy does not examine the entire colon, and focuses only on the lower third of the colon, the sigmoid colon. As such, the sigmoidoscope is typically shorter than a colonoscope, and any abnormalities found during a sigmoidoscopy will still require a follow-up colonoscopy to examine the rest of the colon.

Frequency: Every 10 years (colonoscopy); more frequent screenings at 1-, 3- or 5-yearly intervals required if polyps are found, every 5 years (sigmoidoscopy)

A CT colonography, also known as a virtual colonoscopy harnesses computed tomography (CT) scan technology to visualize the colon and rectum. Coupled with x-rays, the images captured during a CT colonography can be used to construct 3D digital models of the colon and rectum.

Compared to a colonoscopy and sigmoidoscopy, a CT colonography is less invasive and doesn’t require insertion of a scope to visualize the intestinal lining. However, it will still require the bowels to be emptied and prepared for the procedure, as well as ingesting a contrast solution for image visualization. A small tube is also inserted into the rectum to pump air into the colon to ensure clear visuals. While this can cause some discomfort and bloatedness, sedation is not required.

Ultimately, a colonoscopy may still be required if polyps or growths are found in the intestinal lining.

Frequency: Once every five years