Colorectal Cancer Test: Colonoscopy or Fecal Blood Test?


Colorectal cancer screening: patients given a choice more likely to comply. A killer next only to lung cancer, colorectal cancer is the third most diagnosed in men and the second most diagnosed in women worldwide — with over 1.2 million new cases and 700,000 deaths estimated to occur yearly.

But it’s curable when detected early, and the two main screening methods — fecal occult blood test and colonoscopy — can detect the earliest signs. The problem is, too many of the people who have a high risk for the cancer are skipping the tests because of “squeamishness” and lack of awareness.

Now researchers from the University of Washington in Seattle say that people whose doctors let them choose between a colonoscopy or a fecal occult blood test were much more likely to get screened than people whose doctors told them to get a colonoscopy.

This suggests that people are more likely to get screened for colorectal cancer when their doctors take their preferences into consideration before recommending one test or another.

This also means that the current universal practice of doctors recommending a colonoscopy actually reduces adherence to colorectal cancer screening — especially among racial or ethnic minorities in the United States.

Those are the two main findings of a study done by the University of Washington’s Dr. John M. Inadomi, and his colleagues. The results of their randomized study are published in the April 9 issue of the Archives of Internal Medicine.

The study also describes how various racial or ethnic groups vary in terms of their adherence to colorectal cancer screening recommendations.

A colonoscopy involves inserting a tiny camera attached to a tube through the anus into the colon to examine intestinal walls for abnormal growths. A fecal occult blood test, in turn, is a stool test that measures the amount and characteristics of blood in a person’s stool.

Commenting on the research, Dr. Linda Rabeneck, vice president of prevention and cancer control at Cancer Care Ontario in Canada says, “The basic finding here is, when offered a choice, you not only get better screening participation, but also a significant proportion of people don’t choose colonoscopy.”

“There are a lot of factors that are associated with the choice of one test over another,” Rabeneck tells Reuters Health in an interview. “I think this drives it home in a very powerful way,” she says. For one, the report shows people have a lot of different preferences when it comes to picking a test, she adds. Dr. Rabeneck wasn’t involved in the research.

Specifically, the study showed that:
• When given a choice, 69 percent of people get screened for colon cancer within a year
• When their doctor recommended a colonoscopy, just 38 percent of people got one.
• When their doctor recommended a fecal blood test, 67 percent of people went out and got one.
• Overall, 31 percent of the people given a choice went with the colonoscopy, versus 38 percent for the fecal blood test.

Dr. Inadomi and his colleagues also say that by pushing colonoscopies, doctors may be missing out on a chance to get people screened — especially if patients belong to an ethnic or racial minority.

The findings show that when given the choice:
• White people overwhelmingly chose colonoscopy
• African-American, Latino, and Asian participants preferred the fecal blood test.

“So there’s a clear racial split,” Dr. Inadomi, chief of gastroenterology at the University of Washington and lead author of the study tells Shots, the health blog of the National Public Radio. He also notes that until now, most research on colon cancer screening had been done in whites.

Originally, Inadomi’s team were told by psychologists that giving patients a choice would confuse or overwhelm them — and discourage them from making any decision or getting any test. But the findings turned out to be contrary.

In an email interview with Reuters Health, Dr. Inadomi says that, based on the study’s results, he now thinks doctors should give patients choices. “I would make sure that I took into account the patient’s preferences. I would flat out describe these tests… I think this goes against what a lot of us are doing right now. We should be finding out what patients prefer and really pursuing that,” he says.

In a commentary accompanying the study’s results, Dr. Theodore Levin, from Kaiser Permanente Medical Center says, “The study…demonstrates that not having enough choice may lead to inaction when the only choice is colonoscopy.”

Who should be screened?
Globally, the incidence of colorectal cancer varies over tenfold, with U.S., Canada, Europe, Australia and New Zealand having the highest rates and Africa and South-Central Asia having the lowest. Epidemiologists attribute these geographic differences to differences in dietary and environmental exposures more than genetic susceptibility.

According to the American Cancer Society, an American’s risk of developing the cancer over their lifetime is about one in 20.

The U.S. Preventive Services Task Force, a government-backed advisory group, advises all people 50 to 75 years old to be screened by one of three methods:
• a colonoscopy every 10 years
• stool testing annually
• flexible sigmoidoscopy — a less-thorough look into the colon every five years together with stool testing every two to three years

Health Canada advises people 50 to 74 with no family history of colorectal cancer to be screened every two years with a fecal occult blood test (FOBT).

But a number of factors can increase a person’s risk. These include:
• Being 40 years old or older.
• Having certain hereditary conditions, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC or Lynch syndrome).
• Having a personal history of any of the following:
– Colorectal cancer.
– Polyps (small pieces of bulging tissue) in the colon or rectum.
– Cancer of the ovary, endometrium, or breast.
• Having a parent, brother, sister, or child with a history of colorectal cancer or polyps.
• Alcohol use, smoking and obesity. Drinking three or more alcoholic beverages per day increases the risk of colorectal cancer. Drinking alcohol is also linked to the risk of forming large colorectal adenomas.
• Having Gardner syndrome.
• Inflammatory intestinal conditions such as Crohn’s disease or ulcerative colitis, diabetes, and a high-fat, low-fiber diet are known risk factors for rectal cancer.
• Smoking. A 50% increase in risk was associated with smoking more than a pack a day relative to never smoking.
• Lack of exercise. This may increase your risk of colorectal, as well as other cancers.

Squeamishness is uncalled for
According to NPR’s health blog, Shots, one-third of people over age 50 aren’t getting screened for colon cancer, despite a big push from the medical establishment.


“Clearly, colonoscopy has an image problem,” it notes, saying that that isn’t surprising, since “colonoscopy is invasive, inconvenient and expensive,” while a fecal occult blood test, which looks for blood in the stool, is “simple, cheap and just a little bit icky.”

But the procedures aren’t as nasty as people think. Health experts note that fecal occult blood tests are do-it-yourself-kits that can be acquired from a family doctor, a nurse or bought in a pharmacy.

But a positive result calls for a colonoscopy, notes Cancer Canada Ontario’s Dr. Rabeneck. It’s “a very important and very common procedure,” she says Rabeneck but it actually involves little discomfort and a patient can sleep through it. “And it’s good for a day off work,” she tells Reuters Health.

What the researchers actually did
For the study, Dr. Inadomi and his team followed 997 people who were using the San Francisco public health system between April 2007 and March 2010. All of the participants were men and women between 50 and 79 years old with an average risk of developing colorectal cancer.

They then divided the participants into three groups.
• For the first group of 337 people, doctors only recommended colonoscopy
• For the second group of 344 people, the doctors only recommended fecal occult blood testing
• For the third group of 321 people, doctors gave patients a choice between the two tests.

The researchers made every effort to reduce barriers to care by provided the following:
• All written materials were in the participant’s preferred language.
• Patients who chose colonoscopy bypassed a pre-procedure gastroenterological visit.
• All colonoscopies were scheduled within two weeks of enrollment.
• Post-procedure transportation was provided as part of the study.
• Colonoscopy was available to all patients regardless of insurance status.

“We need to realize that if you provide access and an infrastructure even in a low income, low education environment you can get good compliance,” Dr. Inadomi concludes.

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