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Not So Fast– At-Home Screening Test “Cologuard” Is Not A Good Alternative To A Colonoscopy

Published Feb 28, 2019

There have been a lot of stories in the news about an at-home colorectal cancer screening kit called Cologuard. Many have gone as far as to say that they are a good replacement for a colonoscopy. But that isn’t true. Cologuard is not a good replacement for a colonoscopy, according to Dr. Heather Yeo, Surgical Oncologist and Colorectal Surgeon at Weill Cornell Medicine and NewYork-Presbyterian.

Cologuard is an at-home test that helps with some parts of colorectal cancer screening. To use it you order a kit, which instructs you to give a stool sample. Then, you send the stool sample back to the company, which runs some tests to see whether there are any signs of cancerous cells that can be detected in the stool. But stool samples aren’t enough when it comes to colorectal cancer screening.

“There has been some news lately about at home stool tests saying that they are as successful as colonoscopy in picking up early cancers. It’s not quite true. They’re really good at picking up more advanced cancers or cancers, but unlike colonoscopy, they can’t pick up the pre-cancerous lesions called polyps that we need to take out to prevent cancer,” says Dr. Yeo.

A colonoscopy helps doctors look inside the colon, rather than inside the stool. “A colonoscopy is a procedure where under anesthesia, a small scope is placed in the anus and carried all the way in throughout the remaining part of the colon, and you’re able to see growths and take them out before there is a cancer,” says Dr. Zuri Murrell, colorectal surgeon and Director of the Cedars-Sinai Colorectal Cancer Center.

The growths that colonoscopies screen for are called polyps. “All colon cancer starts as these small growths called polyps,” says Dr.  Murrell. And colonoscopies are the only way for doctors to detect the polyps so that they can remove them. “These polyps have no signs, no symptoms. The only way that you can know you have them is if you do a colonoscopy, and you see them, and you take them out during that procedure.  And if you do that, those cannot grow into a colon cancer.”

Cologuard’s information touts the fact that there are no preparations in order to take the test. “There is no special prep or need for time off. Plus, you don’t have to make any changes to your diet or medication,” says Cologuard’s information. In this way, it’s supposed to be a lot less invasive to your daily routine than a colonoscopy, which requires a brief change to your diet and medication that helps to clean out your bowels.

But the preparation is a necessary part of a colonoscopy because it clears the colon of waste, which helps doctors see the inside of it more clearly, so if you cut out the preparation to make the process more comfortable, you’d also cut out some of the accuracy. “It’s really important to have a good bowel prep though. It really makes it so that when you get your scope it’s going to be a more accurate scope and we’re not going to miss anything,” says Dr. Yeo.





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