March 2, 2017 12:54 pm
Updated: March 2, 2017 1:33 pm

Why are colon cancer rates in Gen Xers and millennials in Canada rising?

WATCH: New research from the American Cancer Society shows a sharp rise in colorectal cancers in people as young as their 20s and 30s.

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While rates of colon and rectal cancer are on the decline in older people, they’re steadily rising in millennials and Gen-Xers. It’s a worrisome trend American doctors documented this week, but the phenomenon is occurring in Canada, too.

New research out of the American Cancer Society is warning that those born in 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer compared to their older counterparts born in the 1950s.

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Overall, colon cancer rates are creeping up in young and middle-aged adults. In the U.S. three in 10 rectal cancer diagnoses are in patients younger than 55 , the “sobering” findings suggest.

READ MORE: Important cancer screening tests and when you should get them

Keep in mind, rates of colon and rectal cancer have been slowing down since the 1980s. But, for some reason, there’s been an uptick of cases in people born from the 1980s onwards.

Turns out, identical patterns are occurring in Canada too, according to Dr. Leah Smith, an epidemiologist at the Canadian Cancer Society.

“We’ve seen very similar trends to what’s been reported in the U.S. We are seeing a general decline in incidence rates but that decline is restricted to age groups over 50, but colorectal cancer is going up in people under 50,” Smith warned.

Seven per cent of all colorectal cancers in Canada are tied to people under 50 years old right now.

“It’s a small proportion but what’s concerning is the increase in this age group, especially if we aren’t seeing this in other age groups. It’s a relatively new phenomenon but it’s one we think is important to learn more about,” she said.

READ MORE: There’s ‘strong evidence’ obesity is tied to 11 types of cancer, study warns

Dr. Prithwish De, director of Surveillance and Cancer Registry at Cancer Care Ontario, studied cancer rates across demographics last year. He stumbled upon similar findings after scouring through cancer records from 1981 to 2010.

Colon cancer rates were up 6.7 per cent in the 15 to 29 age group in Canada. It’s an anomaly: while thyroid and breast cancer are common in young women, and testicular cancer is more common in men in this age group, colorectal cancer is conventionally an older person’s disease.

When it comes to young Canadians being diagnosed with this cancer, 20 to 30 per cent don’t have a family history of the disease. Only five to 10 per cent have a genetic disposition, Smith said.

“When you see a diagnosis in someone who doesn’t have a family history of it and is under age 50, that’s concerning because this is not a cancer type that’s seen in this age group,” De told Global News.

READ MORE: Canadian doctors dispel cancer myths to mark World Cancer Day

This isn’t isolated to North America – Smith said research has already pointed to the trend in other parts of the developed world.

It all boils down to lifestyle factors instead of genetics, the experts agree.

“It’s a change in environment and lifestyle. What’s particularly expected to drive this is excess weight – we know that excess weight is one of the major risk factors for adults,” Smith said.

As the number of Canadians who are overweight or obese continues to climb, so will cancer rates, she suggested.

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Lifestyle factors tied to cancer risk include weight, daily exercise and eating habits, alcohol consumption and smoking status. De said a sedentary lifestyle and consumption of processed meat are also factors that need to be considered.

“Our population is becoming more and more sedentary and that’s another area of concern but there hasn’t been enough long-term data to explore that particular avenue,” he explained.

Colorectal cancer starts in the colon or rectum – parts of the large intestine and the digestive system. It’s the second most commonly diagnosed cancer in Canada and the second leading cause of death from cancer in men.

READ MORE: Bacon, booze and obesity are increasing your risk of stomach cancer

In 2016, it was estimated that 26,100 Canadians were diagnosed with the disease. That figure makes up 13 per cent of all new cancer cases that year.

There is screening but it doesn’t start until about age 50. It’s a take-home test in which patients swab a stool sample and mail it to a lab where it’s checked for the presence of blood, an indication that there may be problems in your colon.

Smith said it’s too early to tell if screening should be introduced earlier on. With testing, there is risk of false positives and other issues.

READ MORE: Cancer cases slated to climb 40 per cent by 2030, Canadian report warns

De said these worrisome trends are enough for health officials to consider targeted awareness campaigns to young Canadians so they understand their risk factors for colon cancer.

In the meantime, pay attention to your potential symptoms. Warning signs include diarrhea, constipation, blood in the stool, gas, cramping, bloating and feeling full.

March is Colon Cancer Awareness Month.

READ MORE: Alcohol ‘directly causes’ seven forms of cancer, scientist suggests

Read the full study published in the Journal of the National Cancer Institute.

carmen.chai@globalnews.ca

© 2017 Global News, a division of Corus Entertainment Inc.

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