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Cologuard as a Screening Test for Colon Cancer

“You are due for a routine colonoscopy.” Not everyone’s favorite message from his or her doctor. But colorectal cancer is the second leading cause of death from cancer, and colonoscopy to detect pre-cancerous lesions or early colon cancers has been demonstrated to significantly decrease this death rate.

While most of my patients understand this advice as sound, the process of undergoing a bowel prep and having a colonoscopy remains a point of contention. Two days ago, the FDA approved a new non-invasive test that also screens for both early colon cancers and pre-cancerous lesions, just by providing a stool sample in the privacy of your home.

Cologuard, from Exact Sciences, is a test that looks for abnormal DNA shed by precancerous or cancerous lesions, as well as for blood, in the stool. In a study of over 10,000 patients due for routine screening, Cologuard was compared to the gold standard of colonoscopy and found to have a 92.3% sensitivity in finding cancers and a 42.4% sensitivity in finding pre-cancerous lesions. The negative predictive value was more impressive: if the test was normal, 99.94% of those patients did not have cancer, and 94.79% did not have a pre-cancerous lesion.

This test is NOT currently approved or intended to replace colonoscopy as the primary method of cancer screening; rather, it is an adjunct to that process. It was developed in response to the 23 million Americans who do not go for their recommended screening, despite the clear benefits demonstrated from undergoing routine colonoscopies.

Current screening guidelines dictate a routine colonoscopy to start at age 50, or age 45 for African Americans. Most gastroenterologists recommend repeating this study once every five years. For patients with various risks factors, colonoscopies might be indicated earlier and more frequently – you should discuss your individual risk factors with your doctor.

It is not yet clear who should have a Cologuard test, nor at what interval. However, if you are among the many squeamish folks out there who have refused or delayed your colonoscopy, this test represents a reasonable and easy option to consider. Read more here:

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