Are non-invasive colon cancer screening tests a good alternative to a colonoscopy? - Virtua Article

Is a Non-Invasive Colon Cancer Screening Test a Good Alternative to a Colonoscopy?

By Gregory Seltzer, MD, Gastroenterologist—Virtua Gastroenterology 

If you’re age 50 or older and you haven’t been screened for colorectal cancer, what’s stopping you? 

Maybe you heard that preparing for a colonoscopy can be a bit of a hassle or you’re scared or embarrassed to have the procedure. If so, there are other tests that screen for colon and rectal cancer. Here’s what you need to know about traditional colonoscopies and how they compare to non-invasive colorectal cancer screening tests. 

What is a colonoscopy?

A colonoscopy is the best colorectal cancer screening test and the only screening test that can prevent cancer. A colonoscopy allows a doctor to examine the entire colon for colon cancer and colon polyps. 

During the procedure, the doctor inserts a thin, flexible tube with a tiny camera called a colonoscope through the rectum and into the colon to look for colon polyps and cancer. Colon polyps are growths that can turn into cancer. Colon polyps can be removed during a colonoscopy and this prevents colon cancer in the future.  

Colonoscopies are so effective at preventing colorectal cancer that people who aren't high risk only need to have one every 10 years.  

What are the alternative colorectal cancer screening tests?

Alternative tests to a colonoscopy check for signs of colorectal cancer using a stool sample. There are 3 types of stool tests: 

  • Hemoccult test
  • Fecal immunochemical test (FIT)
  • Cologuard 

The hemoccult test and FIT look for blood in the stool and need to be repeated every year. 

Cologuard identifies blood in the stool and DNA mutations that can be an early indicator for colorectal cancer or advanced precancerous polyps. Cologuard is available by prescription and needs to be repeated every 3 years.

How are stool-based colorectal cancer screening tests different from colonoscopies?

The screening tests above look for signs of colorectal cancer in stool, while a colonoscopy involves a visual examination of the entire colon. 

The U.S. Preventive Services Task Force doesn’t play favorites when it comes to colon cancer screenings. Since 1/3 of Americans between the ages of 50-75 have never been screened, it’s best to offer choices to encourage more people to be screened. 

If you’re weighing your options between a colonoscopy and a stool-based test, here are the key differences to consider. 


  • You must prep the bowels the day before your colonoscopy using a special laxative preparation that empties the bowels, and follow a clear-liquid diet as well. This gives the doctor a clear view of the inside walls of the colon.
  • A colonoscopy is a 20-30 minute outpatient procedure that’s done while you’re under sedation. You’ll need the day off from work and a ride home from the procedure.
  • During a colonoscopy, the doctor can detect and remove polyps in the earliest stage and diagnose advanced colon polyps or colorectal cancer.
  • Depending on the results of your colonoscopy, you may not need another one for 10 years. 

Stool-based colon cancer screenings

  • You don’t have to prep the bowels or change your diet before these tests.
  • With hemoccult, FIT and Cologuard tests, you use a special kit to collect a stool sample at home and then mail it to a lab. A hemoccult test needs samples from 3 bowel movements, preferably from 3 consecutive days. FIT and Cologuard only require 1 stool sample.
  • Stool-based screening tests provide information as to whether there’s blood or a certain DNA mutation present in the stool that indicates colorectal cancer.
  • Stool-based colon cancer screenings can have a higher false-positive rate because a benign condition like hemorrhoids can cause bleeding that’s picked up in the test. 
  • If these screenings detect you’re at risk for colorectal cancer, you’ll still need to have a colonoscopy so the doctor can examine the colon for polyps or cancer.
  • A hemoccult test and FIT need to be repeated yearly; Cologuard needs to be repeated every 3 years. 

Is a colonoscopy or a stool-based screening test right for me?

A colonoscopy is the only test that screens for and prevents colorectal cancer, so your doctor will likely recommend this procedure first. If you can’t or don’t want to have a colonoscopy, a stool-based test is still an option. Just be sure to be screened if you’re age 50 or older or earlier depending your medical history and risk factors. 

If you have concerns about having a colonoscopy, talk to your doctor. It’s normal to feel a little nervous about having a colonoscopy—especially if you’ve never had one before. Your doctor may be able to provide reassurance that puts your mind at ease or suggest some things you can do to make your colonoscopy and the prep more comfortable and convenient. 

Read more about colorectal cancer screening tests and colonoscopy, or call 1-888-VIRTUA-3 to schedule a consultation with a Virtua physician. 

Updated December 3, 2018

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