A surge in global cancer cases for people under the age of 50 has raised urgent concerns about the shifting landscape of this disease among younger populations, according to new research.
The study, published Tuesday in the journal BMJ Oncology, found that in 2019 new cases of early-onset cancers (people aged 15 to 49 years) were 3.26 million, a 79.1-per cent increase from 1990.
While breast cancer made up the highest number of cases in this age group, the fastest-rising cancers since 1990 have been those of the windpipe (nasopharynx) and prostate, the study found.
The researchers found that new cancer cases with the heaviest death toll for young adults were breast, windpipe, lung, bowel and stomach.
“Cancers historically perceived to be more common in older age groups are now being diagnosed in younger adults, including colorectal, breast, oesophageal, gastric and pancreatic cancers, among others,” said Dr. Ashleigh Hamilton, a clinical lecturer at the Centre for Public Health at Queen’s University Belfast, U.K., in an editorial piece on the study. She was not involved in the research.
“It is important to educate both the public and healthcare professionals regarding the possibility of certain cancers in younger adults to allow earlier diagnosis, which in turn improves outcomes.”
In order to find the results, the researchers of the study, based in China, used data from the Global Burden of Disease 2019 Study for 29 cancers in 204 countries and regions.
They then looked at new cancer cases, deaths, health consequences and risk factors for people aged 14 to 49 in order to estimate annual percentage changes between 1990 and 2019.
New cases of early-onset windpipe and prostate cancers rose the fastest between 1990 and 2019, with estimated annual percentage changes of 2.28 per cent and 2.23 per cent. And early-onset liver cancer had the sharpest decrease, falling an estimated 2.88 per cent every year.
In 2019, cancer claimed the lives of over one million people under the age of 50 globally, representing an increase of nearly 28 per cent compared to 1990, the researchers found. The sharpest increases in deaths were found in people battling kidney or ovarian cancer.
The highest rates of early-onset cancers in 2019 were in North America, Australasia, and Western Europe, the researchers said.
The study also forecasted cancer rates for the coming years, saying that, “the projections indicated that the global number of incidence and deaths of early-onset cancer would increase by 31 per cent and 21 per cent in 2030,” with those in their 40s the most at risk.
Dr. Michael Cox, an associate professor of the Department of Urologic Sciences at the University of British Columbia, said although the study showed rates rising across the world, that could be attributed to earlier detection.
“What they’re really talking about here are these prevalent cancers, these cancers of older people and that we’re just detecting them earlier,” he said. “We’re better at diagnosing. We intervene really early.”
Jaylee Thomas, a 42-year-old cancer survivor from Vancouver, said the findings of the study didn’t come as a shock.
Thomas was diagnosed with late-stage three colon cancer a month before turning 33. She believes the stress she had during her 20s contributed to the large tumour that was found growing inside her rectum.
“It’s not a surprise at all. It’s the opposite of a surprise,” she told Global News. “I’m surprised that the people in charge don’t know this already.
“In my experience, is that they can they can give you surgery and they can diagnose what’s wrong with you, but they can’t tell you why you got it, how you got it, how you can prevent it from happening again.”
Receiving a cancer diagnosis at a young age profoundly altered her life, she said, leading her to adopt healthier coping mechanisms for managing stress.
“I was lucky to get it young because if I got it older, I might not have been able to beat it. And so to me, it was like a reset button,” she said.
Why the increase in cancer cases?
While genetic factors may play a role, the researchers suggest that the primary risk factors linked with common cancers for people under the age of 50 are diets rich in red meat and salt, low in fruit and milk, alcohol consumption, and tobacco use. Physical inactivity, excess weight, and high blood sugar are contributing factors in these cases, the researchers added.
“Changes in diet, lifestyle and environment since the turn of the 20th century, resulting in increased rates of obesity, physical inactivity, westernized diets and environmental pollution, may have affected the incidence of early-onset cancer,” the authors state.
Past studies have linked diets that are heavy in processed meats, refined grains, and sugary drinks with an increased risk of developing colorectal cancer.
For example, a 2023 United Kingdom study published in the Lancet found that higher consumption of ultra-processed foods was associated with a greater risk of developing cancer — specifically ovarian and brain.
“Besides their poorer nutritional composition, (ultra-processed foods) may additionally increase cancer risk through neo-formed contaminants during industrial processing, use of some controversial food additives, and certain materials of packaging implicated in exhibiting carcinogenic and/or endocrine-disrupting properties,” the authors of the Lancet study said.
Diet wasn’t the only prominent risk associated with cancer; the BMJ study’s researchers also identified alcohol and tobacco use as major factors contributing to early-onset cancer in 2019. The researchers did not state the frequency.
For early-onset breast, tracheal, bronchus and lung cancers, tobacco smoking was the most important risk factor, followed by diets low in fruits.
Alcohol use was also a leading risk factor for early-onset breast cancer from 1990 to 2019, the researchers found. And smoking and a diet high in sodium were the risk factors for early-onset stomach cancer.
In January, the Canadian Centre on Substance Use and Addiction (CCSA) said that drinking more than two standard drinks — an equivalent of 13.45g of pure alcohol – at a time is associated with increased risks, such as cancer.
In 2020, alcohol use was linked to 7,000 new cancer cases in Canada, including 24 per cent of breast cancer cases, 20 per cent of colon cancers, 15 per cent of rectal cancers, and 13 per cent of oral and liver cancers, according to a global study published in the journal Lancet Oncology.
The researchers of BMJ study acknowledged certain limitations in their work, such as the varying quality of cancer registry data across different countries, which may have resulted in instances of underreporting and underdiagnosis. Also, higher rates of cancer screenings and early life exposure to environmental factors may also be influencing these trends.
“Full understanding of the reasons driving the observed trends remains elusive, although lifestyle factors are likely contributing, and novel areas of research such as antibiotic usage, the gut microbiome, outdoor air pollution and early life exposures are being explored,” Hamilton said in her editorial piece.
Despite the limitations, the authors of the study said encouraging a “healthy lifestyle, including a healthy diet, the restriction of tobacco and alcohol consumption and appropriate outdoor activity, could reduce the burden of early-onset cancer.
“It is worth exploring whether early screening and prevention programmes for early-onset cancer should be expanded to include individuals aged 40–44 and 45–49, but further systematic studies and randomized trials are necessary to make a definitive determination,” the authors said.
The BMJ study said cancer rates were climbing among young people in North America but did not narrow it down by countries in the region.
It is not known exactly how cancer rates are impacting young Canadians, but a 2019 study published in JAMA found that although the incidence of colorectal cancer is decreasing among older adults, rates have increased in adults younger than 50 years.
“Given that younger adults are typically classified as at low risk for the disease, this epidemiologic shift is cause for concern,” the researchers said.
Cancer remains the leading cause of death in Canada, according to the Canadian Cancer Society (CCS). Around two out of every five Canadians will receive a cancer diagnosis during their lifetime, with one in four Canadians dying from the disease.
Between 2015 and 2030, the number of new cancer cases diagnosed is expected to increase by about 40 per cent. The organization said this is largely due to an aging population and increased screening rates.
Lung and bronchus, breast, colorectal and prostate cancers account for almost half of all new cancer cases diagnosed in Canada . Lung cancer is the leading cause of cancer death, responsible for more cancer deaths among Canadians than the other three major cancer types (colorectal, breast and prostate) combined, the CCS said on its website.
“Cancer is a disease that mostly affects Canadians aged 50 and older, but it can occur at any age. Across Canada, cancer incidence rates vary because of differences in risks (including behaviours and exposures) and early detection practices,” the organization said.
— with files from Global News’ Saba Aziz