This screening could MISS deadly cancer!

It's the dark side to one of the biggest cancer screening breakthroughs in decades.

The FIT test takes seconds. You just need to collect a fecal sample in the comfort of your own bathroom and send it off to a lab -- and, if it comes back negative, you're off the hook.

In theory, you DON'T have to get a colonoscopy.

But don't put the colonoscopy in the rear-view mirror just yet -- because a new study finds this test often FAILS in the very people who need it most!

If you have a family history of colon cancer, the FIT test is no better than a coin toss at detecting the warning signs of a potentially deadly form of the disease.

In fact, it's actually slightly worse that that coin flip, spotting advanced neoplasia just 48 percent of the time.

The researchers put that into real-world perspective with some pretty frightening numbers.

Out of every 1,000 high-risk patients, eight will develop colorectal cancer and 94 will have noncancerous advanced neoplasia, a major red flag for the development of the disease.

Yet while the FIT test will detect seven out of the eight colon cancer cases, it will completely MISS a shocking 52 of those 94 neoplasia cases.

If you have a family history of the disease, that's far too big a failure rate.

Don't rest easy if you don't think you have a family history. Some people do, but don't realize it -- especially folks who might be a little older and come from a generation where people didn't speak the word "cancer" out loud.

You might know grandpa died when you were young, but it's entirely possible that no one ever told you that colon cancer claimed his life.

So even if you don't THINK you're at risk, you certainly could be -- and that's not the only problem with FIT.

It has a high rate of false positives of up to 15 percent. When it comes back positive, you have to get a colonoscopy anyway -- but in this case, you don't get to schedule the test at your leisure.

You'll probably call a specialist in a panic... worried sick that the test result means you have cancer... only to be told he's booked for weeks or even months. You'll not only have to wait for your colonoscopy, but you'll be stressed out the whole time, too.

So, while I certainly understand the appeal of the FIT test, it's not for everyone. For most people -- for everyone, really -- there's no substitute for a tried-and-true colonoscopy.

If you've been putting yours off, call your doc and schedule the screening today.