Wading into the colonoscopy controversy
Colon cancer kills a lot of people and causes a lot of suffering.
Almost 52,000 Americans died of colon cancer in 2020.
It’s the second leading cause of US cancer deaths, and those numbers are rising in young people.
And that doesn’t include the morbidity from colon cancer. Lots of these patients need surgery or chemotherapy. Some end up with colostomies.
Preventing colon cancer can save a lot of lives and potentially alleviate a lot of suffering.
So the NordICC trial, a recent randomized trial on the impact of inviting people to participate in screening colonoscopies, created quite a bit of controversy on whether we’re wasting a lot of money on colonoscopies that don’t save lives.
The NordICC trial showed that inviting people to be screened with colonoscopy didn’t reduce deaths from colon cancer or save lives
The intervention in the NordICC trial was simple: participants were randomized to be invited to receive a screening colonoscopy versus not receive an invitation for screening.
The people in the uninvited group did not have the ability to get colonoscopies.
About 42% of the people invited for screening ended up getting screened and they followed people for 10 years.
Risk of death was the same between the groups: 11.03% of people in the invited for screening group died compared to 11.04% of the usual care group.
Risk of death from colon cancer was also similar: 0.28% in the invited group, 0.31% in the usual care group.
It’s a pretty unimpressive set of results for a test that’s heavily marketed as life saving.
I wouldn’t be surprised if you haven’t heard about this trial yet
I’m kind of shocked that this trial wasn’t very well covered in the popular press. The New York Times didn’t mention it. The Washington Post did, but only to tell you that you shouldn’t skip your colonoscopy based on these results.
And, of course, as with everything, there are a huge number of caveats before just concluding that colonoscopies are worthless.
Just a few of the important potential points raised about the limitations of NordICC:
As mentioned above, only 42% of the patients offered screening actually got it
If you just analyze the people who had colonoscopies, the results look much more promising
Because of the long lag between detection and removal of a polyp during a colonoscopy and that polyp turning into a life threatening cancer is so long, we might see a benefit if we follow the patients for a longer time
People who decided to be screened may have been at higher risk, making colonoscopy look less effective
Rates of colon cancer were lower in the invited group who didn’t get screened than in the group that wasn’t invited to be screened
And, perhaps most importantly, this trial didn’t actually test the impact of getting a colonoscopy, it tested the impact of being invited to undergo screening.
Or, summarized in a viral tweet:
Keep in mind that screening for colon cancer has strong evidence behind it
We have tremendous evidence that screening for colon cancer via techniques other than colonoscopy prevents colon cancer and saves lives.
There’s evidence to support doing stool testing (something called FIT (fecal immunochemical testing) to look for microscopic evidence of blood. FIT is done once a year.
There’s also strong evidence that doing a partial colonoscopy - something called a flexible sigmoidoscopy (AKA flex sig) - to look only at the very end of the colon saves lives.
So remember that NordICC just tells us about one screening modality - it isn’t a final word on all types of colon cancer screening.
Part of the benefit of screening for colon cancer is that we can cure preliminary stages
Colon cancer starts has a very clear progression from an abnormal growth to a full blown cancer:
This process takes years to occur, so finding a polyp in the colon early on in this progression enables us to remove it and prevent it from ever turning into cancer.
If everyone had a colonoscopy every single day of their lives, no one would ever die of colon cancer because we would find polyps and remove them before they caused cancer.
Colonoscopy is terrific because it’s not just a diagnostic - it’s also a treatment. During a colonoscopy, the gastroenterologist can remove a polyp well before it causes any problems.
If you have abnormal results of any test - from FIT to flex sig to other imaging - a colonoscopy is always the next step because of how it enables interventions like polypectomy and biopsy.
What should we take from this trial?
I think it’s safe to draw a few conclusions:
Colon cancer screening reduces death from colon cancer and saves lives.
Colonoscopy is not the only way to screen for colon cancer.
Colonoscopy is really safe when done by an experienced operator.
Being invited to get a colonoscopy is not the same as getting a colonoscopy.
A colonoscopy isn’t a free lunch. The prep - having diarrhea for about 12 hours - is pretty unpleasant. It requires time off from work and anesthesia during the procedure.
We shouldn’t confuse the lack of effectiveness shown in NordICC as proving a lack of efficacy.
In other words, something that doesn’t work across a population may still be useful for an individual.
So much of medicine is about separating the small numbers of vulnerable people at risk from everyone else
As with most things in medicine, what you recommend for the population is frequently different than what you recommend for an individual patient.
The job of a physician is to figure out which people benefit from more intensive screening and which people can take the less intensive route.
That means understanding which of our patients are at highest risk and who is most vulnerable.
If someone has inflammatory bowel disease or a family history of early colon cancer, they’re uniquely vulnerable and NordICC doesn’t apply.
But if a patient is at average risk, NordICC suggests to me that FIT or flex sig are completely reasonable alternatives if someone doesn’t want to have a screening colonoscopy.
If I were a policymaker, or an insurance company executive, I don’t think I’d be willing to pay for colonoscopies for the average person.
But I don’t think there’s anything wrong with choosing a colonoscopy as your screening test of choice.
Like most things in medicine, making an individual choice about colonoscopy based on an individual’s personal level of risk is the right way to move forward.