Overuse of Antibiotics Could Be Linked to Rise in Early-Onset Colorectal Cancer, Says One Expert

While diet, heredity and other factors play a role in the development of cancer, a new hypothesis credits the recent rise of early-onset colorectal cancer (CRC) in younger adults to the possible overuse of childhood antibiotics, says Dr. Mark Lewis of Intermountain Healthcare.

In an interview about how Chadwick Boseman’s death has highlighted the rising prevalence of CRC in younger adults, Lewis, who is a cancer survivor himself, explained the process by which polyps in the colon degenerate into cancer, and how the overuse of antibiotics could be altering the gut microbiome of young patients, potentially leading to the development of these polyps earlier in life.

The idea is only a hypothesis at this point, says Lewis, “But when you look at all the other potential factors, whether it's diet, smoking, alcohol (or) obesity, arguments have been made for and against all those things. And truly, it's some sort of complex interplay between our environment, our lifestyle, our heredity and then just chance, but regardless, the antibiotic theory right now at least seems to hold quite a bit of water.”

Transcription:

Most colon and rectal cancer starts as polyps. So, the real question is: When are the polyps starting, and then when are they degenerating into cancer? So, in their most benign form, a polyp will take something like 15 years from when it first protrudes into the bowel until it actually becomes cancerous. There are, however, other polyps that go much more quickly, and that process can take maybe one to three years.

So, I think what we're seeing happening is that many people are getting polyps at a younger age than we previously saw. And so now by the age of say, 40 to 45, if you screened everybody with colonoscopy, you’d probably find that maybe a quarter of patients have at least one polyp. And again, that polyp is typically going to be precancerous.

But in some people who have been unfortunate enough to develop them earlier, those polyps have already generated into malignancy and that's the people that we're seeing with young-onset colorectal cancer.

Now, the reasons for that are still a little bit mysterious, I have to admit. One theory that I think holds quite a bit of credence, though, is the notion that our younger patients were more likely to be exposed to antibiotics during childhood. And it's interesting, my wife is a primary care doctor, also a pediatrician, and pediatricians have been under enormous pressure for a long time to prescribe antibiotics to sick children. As a parent myself, I understand when my child is ill, and I take him to the doctor, I want not an easy fix, but a relatively quick fix. I don't really want to be told this is a viral illness that will take its course. So, there has been a lot of prescribing of antibiotics in pediatrics, and a lot of it is inappropriate.

Some of it, however, has been pressurized, frankly, by parents. And so, we know, going back several decades now with this uptick in antibiotic use, that we've probably been changing the gut microbiome of young patients. And there is particularly interesting work out of Britain, which has a nationalized health service, we can actually track back from the patients who now have colorectal cancer and see what kind of antibiotics they had in their childhood and in their infancy. And I think that's pretty compelling.

I think what happens is the bacteria in the gut lining change, and the ones that are potentially more likely to cause cancer sort of become dominant and suppress the good bacteria, if you will. So, it's only a hypothesis. But when you look at all the other potential factors, whether it's diet, smoking, alcohol, obesity, arguments have been made for and against all those things. And truly, it's some sort of complex interplay between our environment, our lifestyle, our heredity and then just chance, but regardless, the antibiotic theory right now at least seems to hold quite a bit of water.