Rates Of 11 Cancers Are Rising For Under-50s

Usually, older age is a risk factor for cancers. That’s partly why most cases occur in over-50s. In fact, a third of cases are found in people aged 75 and over.

But according to new research published in BMJ Oncology, two cancers have bucked that trend in England: ovarian and bowel cancers are rising only in younger adults (those under 50).

Meanwhile, multiple other cancers were rising faster among younger people than those over 50, though cases were still increasing for both groups.

Researchers looked at data from the National Disease Registry Service. They found that between 2001 and 2019, incidences of 16 out of 22 cancers in younger women, and 11 out of 21 cancers in younger men, went up “significantly”.

There were 11 cancers that had known behavioural risk factors for younger people and saw especially high rates. These included:

1. thyroid,
2. multiple myeloma,
3. liver,
4. kidney,
5. gallbladder,
6. pancreatic,
7. womb lining (endometrial),
8. mouth,
9. breast, and
10. ovarian cancers.

People over 50 saw incidence rates of nine of these increase during this period, too.

Bowel and ovarian cancers were the exceptions: they only seemed to rise among under-50s.

Endometrial, kidney, pancreatic, multiple myeloma and thyroid cancers, however, “increased significantly faster in younger than in older women, while multiple myeloma increased faster in younger than in older men,” a BMJ press release reads.

This was an observational study, meaning we can’t say from its data that one thing caused another.

Aside from mouth cancer, the researchers noted that all of the 11 cancers were linked to obesity. Six (liver, bowel, mouth, pancreas, kidney, and ovary cancers) were linked to smoking, while four (liver, bowel, mouth, and breast) are associated with a high alcohol intake.

Bowel, breast, and endometrial cancers are linked to physical inactivity, and bowel cancer is associated with dietary habits like not eating enough fibre and consuming too much red meat.

But the researchers note that with the exception of obesity, younger people have done better or the same as their older peers on these metrics in recent years. Red meat consumption has been down by about 7% in recent years: most of us are eating more fibre, or the same amount, as we did before 2009.

“These patterns suggest that while similar risk factors across ages are likely, some cancers may have age-specific exposures, susceptibilities, or differences in screening and detection practices,” the researchers write.

And plenty of the factors people have previously suggested as a possible cause of rising cancer rates among younger people – including ultra-processed foods, childhood obesity, physical inactivity, antibiotic use, sweetened drinks and air pollution – have “shown stable or declining trends in the last decade”.

In short, it’s a bit of a head-scratcher.

The study authors wrote that they didn’t look at all the possible causes of these increases, adding that there might be more than one reason rates have gone up.

“Other contributing factors not evaluated here, for example, reproductive history, early-life or prenatal risk factors, and changes in cancer diagnosis and detection practices, may also play a role,” they said.

“Although overweight and obesity are linked to 10 of the 11 cancers evaluated and account for a substantial proportion of cancer cases, both BMI-attributable and BMI-non-attributable incidence rates have increased – though the latter more slowly – suggesting other contributors,” they added.

The scientists also said that changes to our gut microbiome might be a factor worth investigating.

But it’s important to remember that the majority of cancer cases still happen among over-50s, they added.

“Although increases in cancer in younger adults are concerning, the absolute burden remains far higher in older adults, underscoring the public health and clinical importance of studying risk factors across all ages.”