These 17 cancers are on the rise in younger generations

Several cancers may be affecting millennials and Gen-X more than they did baby boomers, according to a new study based out of the U.S.

The study, published in The Lancet this month, found that 17 of the 34 most common cancers diagnosed between the ages of 25 to 84 are on the rise in younger people. More than half of the cancers are linked to obesity, consistent with the rise in childhood obesity among recent generations. Without proper intervention, the study’s authors warned that the burden of cancer as younger generations age could not only impact those diagnosed, but also caregivers and society as a whole.

The rise in cancer rates was particularly evident in millennials born around 1990. The number of new cancers of the small intestine, kidney and pancreas was two to three times higher in people in their mid-30s than in boomers — specifically those born around 1955.

Other trends identified in the study were sex-specific, including the incidence of liver cancers increasing among young women.

Miranda Fidler-Benaoudia, an epidemiologist at the University of Calgary and a co-author of the study, said that along with an increase in the diagnoses of several cancers, including endometrial, gallbladder and other biliary, testicular and colorectal cancers, death rates also rose.

“What we want to understand now is why are these individuals not only being diagnosed with cancer at younger ages, but why are they also facing poorer outcomes than the generations before them,” she said.

Generational lifestyle shift

The study looked at cancer and mortality data retrieved from the North American Association of Central Cancer Registries and the U.S. National Center for Health Statistics for individuals aged 25-84 from 2000 to 2019 — data that covered 94 per cent of the U.S. population.

Ten of the 17 cancers increasing in incidence among young people were linked with obesity. The study said that since the late 1970s, the “obesity epidemic” has been affecting Americans across all age groups — with the most affected age group being those between the ages of two and 19.

There are many differences in lifestyle and health care on the Canadian side of the border. When the rate of childhood obesity hit almost 17 per cent in the U.S., Canada’s rate was lower at 13 per cent, according to a 2016 study from Health Promotion and Chronic Disease Prevention in Canada.

“While similar geographically there are a lot of differences we need to replicate this study to be sure these trends are also not happening here,” said Fidler-Benaoudia.

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Even for those who are a healthy weight, the study found that diet may be associated with an increased risk of cancer.

The rise in digestive tract cancers, for instance, including those of the small intestine and other cancers not associated with obesity, could point to generational changes in the types of food people are eating.

“The way we live, the way we eat, the way we prepare our foods, the way we consume our foods, all of those things have a role,” said Dr. Shady Ashamalla, a surgical oncologist at Sunnybrook Health Sciences Centre’s Odette Cancer Centre in Toronto.

Consequences of early-life cancer

About 10,000 Canadians under 40 were expected to be diagnosed with cancer in 2023, representing four per cent of cancers diagnosed, according to the Canadian Cancer Society.

“We don’t want to freak people out, these are still very low numbers, overall,” said Ashamalla, who was not involved with the study.

Still, he says he’s noticed more colorectal cancer patients in their 30s and 40s now than he did at the beginning of his career, 15 years ago.

Ashamalla explained that people diagnosed with cancer at a young age not only have to deal with the immediate health burden, but also the burden on their personal lives.

He said that for cancer patients who have young children, demanding jobs and busy lives, “this is a bomb that has been dropped on their life.”

Fidler-Benaoudia said that people who are diagnosed with cancer at a young age are at an increased risk for chronic health conditions, premature mortality and poor mental health — which can in turn affect education and work prospects.

Without effective population-level interventions, the study suggested that an overall increase in cancer burden could occur in the future as younger generations age — impacting both individual caregivers and wider society.

Lifestyle changes made for the better

While boomers may have had lower rates of childhood obesity and more active lifestyles in their youth, younger generations have had their share of health wins.

The study found that cancers of the head, mouth and neck have been on the decline in young men — a shift that the study’s authors suggested may be attributable to decreases in smoking and alcohol consumption.

In contrast, these same cancers increased among young women, consistent with changes in alcohol-related behaviours among women born in the 1970s and 1980s. Binge drinking accelerated from 1990 to 2010, when these women would have been between the ages of 30 to 49.

Cancers associated with smoking, including lung cancer, have had a strong downward trend that the study said may be attributable to a rapid decline in smoking among young people. Of those who are diagnosed with lung cancer, fewer have been dying of the disease, which the researchers suggested reflects both successful prevention and treatment.

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Screening and prevention changes

Many cancers can be linked to lifestyle choices, but Ashamalla said he regularly sees patients with healthy lifestyles who don’t meet any of the risk factors.

For patients who are otherwise healthy, diagnosis can come as a shock. Guelph resident Bryna Dilman, 45, found herself in this situation back in 2020.

Dilman had blood in her stool, but no other signs of cancer, so when her doctor ordered a colonoscopy for her, she thought about cancelling it, but reconsidered.

When the results came in, she was quickly diagnosed with colorectal cancer. Dilman says she’s grateful her doctor didn’t brush aside her problems, and actively took steps to ensure she was properly diagnosed.

“I would have never thought of something seriously wrong with me, being so young and healthy,” she said.

The Canadian Task Force on Preventive Care recommends screening for colorectal cancer, a cancer that the study showed increased both in incidence and deaths among young people, start at age 50. Ashamalla says this age should, and likely will, change to 40.

The U.S. Preventive Services Task Force recently changed their recommendations to expand screening for colorectal cancers. Previously, only people 50 and over were screened, but screening is now recommended for people 45 to 49 years old, but no Canadian province or territory is currently considering this shift.

“We are actually winning in the population over 50,” said Ashamalla. “Those colorectal cancer rates are going down in populations that we are screening and so screening is absolutely the key.”

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