Certain cancers are becoming a bigger problem for just about everyone. New research shows cases of several obesity-related cancers have been rising across the globe and across different age groups.

Scientists in the UK examined cancer surveillance data spanning 15 years from dozens of countries, including the U.S. They found that, in most countries, several cancer types had increased in both younger and older adults, all of which are linked to obesity. The findings suggest that the surge in cancer cases seen recently isn’t just limited to the young, as some past research and media reports have highlighted.

A widespread rise

Numerous studies have spotted a rise in specific cancers among the young. Earlier this summer, for instance, Dana-Farber researchers reported a steady increase of gastrointestinal cancers in Americans under the age of 50, dating back over a decade.

The researchers behind this current study wanted to take a more expansive look at recent cancer trends, however, both internationally and across the lifespan.

They analyzed data on annually reported cancer cases between 2003 and 2017 from 42 countries in Asia, Europe, Africa, North and South America, and Australia. They focused specifically on 13 types of cancer that past studies have shown may be increasing in young adults.

In most of the countries, the researchers found a clear rise in 6 cancer types among adults under the age of 50 during those years: thyroid cancer, breast cancer, colorectal cancer, kidney cancer, endometrial cancer, and leukemia. But they also found a similar increase in new cases among older adults for five of these cancers. The sole exception was colorectal cancer; an increase of these cases in older adults was only seen in half the countries, and the rate of this increase was generally larger in younger adults.

Interestingly enough, rates of liver, oral, esophageal, and stomach cancer also actually decreased for younger people in more than half the countries studied.

What this means for cancer prevention

The findings, published Tuesday in the Annals of Internal Medicine, don’t mean that the reported cancer rise in young adults has been a mirage. But it does complicate things.

If cancer cases are generally rising across age groups, for instance, that suggests risk factors common to most everyone are to blame, rather than something only affecting young adults. That’s important to know, since scientists and health organizations might otherwise focus only on studying or trying to reverse this rise in young people. Notably, all of the cancer types that might be increasing in both younger and older adults are linked to obesity—a condition that has become more prevalent throughout the world.

“These findings can help inform future research and clinical and public health guidelines,” the authors wrote in their paper.

At the same time, the still apparent difference in colorectal cancer trends points to unique health risks that younger people might be facing. Some research has indicated that younger people could be getting exposed more to certain gastrointestinal infections, for instance.