December 04, 2016
Colon Cancer Screening Choices
Be Well

Colon Cancer Screening Choices

by John Swartzberg, M.D.  |  

You’re a healthy 55-year-old and at no increased risk for colon cancer (more precisely cancer of the colon or rectum, together often called colorectal). Should you be screened? Absolutely.

Colon cancer is the second leading cancer killer among men and women, jointly, in the United States, after lung cancer. Screening can identify colon cancer before it has spread, leading to a life-saving surgical procedure. It can also find polyps, benign growths—some of which have the potential to eventually become malignant. And almost all colon cancer begins on certain types of polyps, so screening for polyps (and subsequently removing) them will prevent colon cancer, very much like Pap smears and/or HPV testing prevent cervical cancer.

But how should you be screened? This question has generated a big debate in the medical profession.

If you ask most people, I bet the answer would be colonoscopy. Many doctors would say the same thing. Certainly, the American Gastroenterological Society would agree—it‘s an organization of physicians, researchers and educators whose primary practice or research involves the functions and disorders of the digestive system.

At first blush it makes sense that colonoscopy should be the test of choice as it allows the doctor to look at the entire colon. But, there are downsides: it’s very expensive; it must be performed in a specialized center; it requires thorough cleansing of the colon (the dreaded colonic prep which necessitates spending most of the preceding evening in the bathroom). And it requires intravenous sedation. Even though most of the time the entire colon can be visualized, it’s easy to miss lesions on the side furthest away from the rectum. Finally, it carries a very small risk of complications, especially colonic perforation (I’ve seen three or four cases of this over the years—all requiring major surgery to correct the problem).

Another problem with colonoscopy: there are not enough gastroenterologists to meeting the public’s needs. In 2009, The Lewin Group reported that there are 10,390 practicing gastroenterologists in the United States. Using the 2010 census data, about 18 percent of the population is between 50 and 75. Assuming that most of these people should have a screening colonoscopy every 10 years (those at higher risk need it more often), every gastroenterologist would have to do about 600 colonoscopies a year. That would not leave a lot of time for the other critical health roles gastroenterologists play.

Fortunately, there are alternatives to colonoscopy that may be comparable in efficacy and much less expensive, can be performed without anesthesia in a doctor’s office and are safer. I’m referring to a combination of testing the stool for evidence of blood (the best test is called the fecal immunochemical test or FIT) and sigmoidoscopy (sigmoidoscopy visualizes the rectum and part of the left side of the colon).

Preliminary data suggests that this approach is comparably effective to colonoscopy. Longer term studies should be available in the next few years to know for sure.

The Centers for Disease Control and Prevention (CDC) calls for adults at average risk for colon cancer aged 50 years and older to be screened with one or a combination of the following tests: a fecal occult blood test (FOBT) or fecal immunochemical test (FIT) every year; flexible sigmoidoscopy every five years, with FOBT/FIT every three years; or colonoscopy every 10 years.

Yet, 90 percent of those who get screened have a colonoscopy. Largely, this is because the public has been taught that this is the best test. It’s recommended by the American Gastroenterological Association. Some say this may be self-serving. After all, there’s a lot more money to be made by doing this procedure—much more than spending time doing a thorough medical consultation. And gastroenterologists are the doctors who perform almost all colonoscopies.

The important point that’s lost in this debate is that too many people are not being screened at all. A recent CDC report found that one-third of Americans between 50 and 75 haven't been screened as recommended. It’s frustrating: Despite the very good screening tools we have to prevent colon cancer, too many people aren't screened and a disproportionate amount of energy goes into how we screen. According to CDC Director Tom Frieden, “There are more than 20 million adults in this country who haven’t had any recommended screening for colorectal cancer and who may therefore get cancer and die from a preventable tragedy...Screening for colorectal cancer is effective and can save your life.”