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Colorectal cancer on the rise in younger patients: Should screening age change?

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Both U.S. and Canadian data show colorectal cancer rates are on the rise among younger adults — but there’s no change in screening policies on the horizon for Canada yet, according to one expert.

A new report from the American Cancer Society (ACS) published at the beginning of March found that cases of colorectal cancer in Americans under the age of 55 now make up 20 per cent of total cases across the country.

This is nearly double the rate of colorectal cancer in this age group in the U.S. 30 years ago.

And the Canadian data shows a similar uptick. According to a 2019 study in JAMA Network, from 2006 to 2015 there was a 31 per cent increase in younger adults being diagnosed with colorectal cancer.

In the U.S., screening for colorectal cancer has been recommended starting at 45 years old since 2018, but Canada still recommends it start when a patient reaches 50 years old.

Colon cancer usually impacts older people. So why are we seeing more cases in younger adults?

Tom McFarlane, a clinical oncology pharmacist based in Waterloo, Ont., told CTV’s Your Morning that scientists “don’t know exactly why” at this stage, although there are theories.

“There’s obviously lifestyle factors that could be implicated here — by lifestyle factors I mean obesity, poor diet, alcohol intake and so forth — but those increase the risk for pretty much everybody, so there’s something that is happening that is not entirely clear,” he said.

“There are probably some combination of risk factors that are yet to be determined that researchers haven’t found yet.”

According to the ACS report, the U.S. is seeing more cases of advanced stages of colorectal cancer as well. In the mid-2000s, 52 per cent of colorectal diagnoses were advanced-stage cases, but in 2019, it was 60 per cent.

In 2023, it is estimated that more than 153,000 people will be diagnosed with colorectal cancer in the U.S., and 52,000 people will die, the report found.

“We know rates are increasing in young people, but it’s alarming to see how rapidly the whole patient population is shifting younger, despite shrinking numbers in the overall population,” Rebecca Siegel, senior scientific director of surveillance research at the American Cancer Society and lead author of the report, said in a press release. “The trend toward more advanced disease in people of all ages is also surprising and should motivate everyone 45 and older to get screened.”

McFarlane said that while the rise in younger patients getting diagnosed with colorectal cancer is concerning, it’s unlikely to spur a screening recommendation change at this stage in Canada.

“I guess it depends on what the trends are, but it’s possible that we need to revisit it if we see these rates continue to rise,” he said. “However, for now, we’re still recommending the screening to be done in patients 50 and over.”

He added that younger adults who have a close relative with colorectal cancer, or a family history, are encouraged to receive regular screening earlier.

One of the main issues that doctors face when younger Canadians develop colorectal cancer is that they are less likely to pay attention to early signs, he said.

“I think actually the challenge that we run into more often than not with younger patients is that they ignore the symptoms, because they don’t think that it’s likely going to be colorectal cancer that is causing these symptoms,” McFarlane said.

“If you have a younger patient who ignores symptoms, the cancer will potentially progress to the point where it’s at a higher stage, and at that point it’s much more difficult to treat.

He believes that rather than changing screening recommendations, the most important thing to aid younger adults in terms of diagnosis is to stress an awareness of the symptoms.

“That includes things like blood in the stool, that includes things like unusual shaped stools or changes in bowel habits where you have diarrhea or constipation for a period of a couple of weeks when you’ve never had it before,” he said. “And also severe fatigue that can’t be explained in any other way.”

These are all symptoms that should be mentioned to your doctor if you are experiencing any of them, he said.

“As far as screening is concerned, we don’t really have evidence to change our screening policies at this point,” McFarlane said.

“We usually base those on epidemiological data or screening data that shows us that it’s cost-effective or that it’s useful.”

He said the current data doesn’t suggest a change in screening policy would balance these interests yet.

“These are still a fairly low number of the overall cases that we’re seeing, even though we’re seeing this sort of rapid rise,” he said.

There are some positive signs in the ACS report, including that the incidence rates of colorectal cancer are declining in those aged 65 and older, and have been since 2011.

However, the incidence rates have increased two per cent per year since then in people younger than 55 years of age.

And if incidence rates continue increasing in Canada as well, the question of screening may come up again.

“We may need to revisit this and talk about it if we continue to see these cases rise in the younger adult population,” McFarlane said.

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