Dr. Kohli On Colon Cancer Screening

By Payal Kohli, MD, FACC - Last Updated: November 14, 2022

Colorectal cancer is the third most common cancer in the United States, according to the American Cancer Society. It is expected to kill 52,580 Americans this year alone. What’s more, cases of colorectal cancer are trending younger and younger. Colonoscopy is the gold standard for early detection of this deadly disease, but a recent study suggests that colonoscopies may not be effective for reducing colon cancer diagnoses and deaths.

DocWire News spoke with our Medical Lead, Dr. Payal Kohli, who gave her thoughts on the study, and why she feels the findings are flawed and that colonoscopies do in fact save lives if you get them.

DocWire News: Talk to us about colon cancer – are bases of colon cancer on the rise, and what’s the prognosis for advanced colon cancer?

Dr. Payal Kohli: What’s interesting is during the last two years of the pandemic, we’ve actually seen a 40% decrease in colon cancer diagnoses. This doesn’t mean we’re not having colon cancer, this means we are not diagnosing it. And this really worries me because we’re still collecting data, but my concern is that this translates into more late stage cancers being diagnosed, and we know that if colon cancer is found early, it can be cured with a very high survival rate of 94%. Whereas if it’s found late, it has a very low survival rate and a very poor prognosis. And we do know that colon cancer is the second leading cause of cancer death. And so it’s a big cancer, it’s got a high burden. And we’re also seeing a very interesting trend where we’re seeing more and more younger patients now being diagnosed with colon cancer and fewer older patients being diagnosed with colon cancer.

And the reason for this is because we had spent so much time really doing screenings and colonoscopies in our older and geriatric population that in a way we almost sort of neglected the younger population. And because of some of these disturbing trends, the new guidelines actually now recommend for an average risk person to start their colon cancer screening, not at the age of 50, but actually at the age of 45. So they’ve moved it down because we’re seeing more and more younger people starting to present with cancer even before they were eligible to get screened.

How effective are colonoscopies at early detection of colon cancer?

It’s a million dollar question because colonoscopies have really been the gold standard for what we’ve thought of as really the best way to detect colon cancer. And some of the data that we have comes from earlier observational, non-randomized studies about colon cancer detection and prevention of death. And the numbers are kind of widely variable, but we see from about 40 to about 70% reduction in colon cancer diagnosis and about 30 to about 90% reduction in colon cancer related death. But again, it’s a wide range and a lot of that data comes from observational studies of the people that are getting colonoscopies may inherently be different than the people that are not getting colonoscopies. So it’s a little hard to know whether that’s true data or whether there’s still some confounding that hasn’t been accounted for in the observational trial. So that’s why a randomized trial is really the best way to know cleanly whether an intervention has an effect, and really to quantify what the effect of that intervention is.

Talk to us about the study recently published in NEJM about colon cancer screening. How was the study conducted, what were the findings, and do you agree with the findings?

Yeah, so it got a lot of attention, and it is that randomized trial that we’ve been looking for, and it’s a first ever randomized trial of colonoscopies for preventive cancer therapy screening. And it asks the question of, does an invitation to get invited to have a colonoscopy prevent cancer and save lives as opposed to not getting that invitation? So it took a large number of people, over 80,000 people, and it randomized them to either getting invited to get a colonoscopy or not getting any special invitation or cancer screening outside of the usual care. And then it counted up who had how many events and who got diagnosed with colon cancer. So if you look at the people that were randomized to get an invitation versus those that weren’t, there was a meager difference in the outcomes. There was only an 18% reduction in cancer diagnosis and really no statistically significant reduction in cancer death.

But here’s the big problem with the study, because they randomized somebody to get invited to have a colonoscopy. If you actually change the analysis from an intention to treat, which is where you randomized to, to an on treatment, which actually tells you what intervention you actually got, in the on treatment group, the patients that went on to have a colonoscopy, which was only 42% of the ones that were invited, you saw dramatic decreases. You saw 31% reduction in colon cancer diagnoses and 50% reduction in colon cancer death. So in my opinion, the study was a little bit flawed in its design because it asked the question of does an invitation to get a colonoscopy save lives or prevent cancer as opposed to the colonoscopy itself, which I truly believe is still a very important valuable intervention.

What would you say to someone who looks at this study, and is hesitant about getting a colonoscopy?

I would say the headlines are wrong here and all over media, social media and everywhere else the headline is “colonoscopies don’t save lives” and that is not the take home message. The take home message is that cancer screening is imperative. Colon cancer is a huge burden, and colonoscopies do save lives if you actually go and get them. So I would say you want to be real careful because sometimes when we’re interpreting clinical trials, for the sake of being pure, we have to give the intention to treat analysis because we have to show the entire group that was randomized to the invitation whether they got it or not. But the majority of them, 58% of them didn’t even actually get the intervention, so that’s just diluting out our signals. So don’t get carried away. The colonoscopy is still the gold standard for screening according to all the experts and then the Cancer Society Prevention guidelines as well.

And the age to get started is 45 for average risk. If you have a family history of a relative, then you want to start much earlier, usually about 10 years before that relative was diagnosed with colon cancer. So this is a preventable cancer with the right interventions. Now, I’m hopeful as I get older that many years down the line, maybe there’ll be a better method for screening for colon cancer, a non-invasive method potentially. And that data remains to be seen. But for now, today in 2022, we have to tell our patients that those headlines are a little bit misleading and we need to debunk them and really tell them that colonoscopies are the way to prevent colon cancer.

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