The number of people under the age of 50 diagnosed with cancer has increased by 24% in 20 years, a greater increase than in any other age group. According to figures, this is likely linked to rising obesity rates, cheap junk food and inactivity.
The incidence of premature illness grew from 132.9 per 100,000 people in 1995 to 164.6 in 2019, data analysis shows. About 35,000 young people under the age of 50 develop cancer every year, almost 100 young women and men every day, the study found.
Meanwhile, concerns are growing that a global cancer epidemic could emerge among young people. The explosion in cases was a major focus this weekend at the world’s largest cancer conference, the annual meeting of the American Society of Clinical Oncology (ASCO).
Experts are still in the early stages of understanding the reasons behind the increase in cases. But most believe poor diet, physical inactivity and obesity are likely to be among the factors behind the rise in cancer rates among young people in Britain.
Incidence rates have increased across all ages over the past two decades. But the 24% increase among those under 50 is much higher than the increases among other age groups.
Professor Charles Swanton, chief medical officer at Cancer Research UK, said: “Over recent decades there has been a marked increase in the incidence of cancer in young adults in Britain. There is evidence that more adults under the age of 50 may be developing cancer than ever before.”
The second largest increase in cases occurred among those under 25 years of age. Their rate increased by 16%, from 16.6 cases per 100,000 in 1995 to 19.2 in 2019.
According to Cancer Research UK’s analysis, the overall incidence rate of cancer cases at all ages has risen from 539 per 100,000 people in 1995 to 611.5 in 2019. That represents an increase of 13% – almost half the growth rate among the over-50s.
In the age group from 50 to 74 years, the incidence rate increased by 14%, from 955.1 to 1,092. Among people over 75, there was an increase of 10%, from 2,259.7 cases per 100,000 people to 2,482.7 cases. This means that the interest rate increase among the over-50s was more than double that of the over-75s.
Early-onset cancers are still uncommon. About 90% of all cancers affect people over the age of 50.
But the trend was still “concerning,” Swanton said, with 34,945 cases in 2019, according to the analysis. That total is 34% higher than the 26,176 in 1995. The reason the percentage change is greater than the 24% rate increase is likely due to population growth.
“While these cases represent a small proportion of the overall population and are still relatively uncommon, the trend is important and requires further investigation,” Swanton said.
Researchers are still in the early stages of figuring out why cancer can become a disease of the young, but there are already clues, he said.
“Increased exposure to both known and unknown risk factors for cancer, changes in lifestyle and diet over time, and increasing obesity rates may all contribute to the increase in early-onset cancers.” Swanton said.
Britain has one of the highest obesity rates in Europe, with two in three adults in Britain being overweight or obese.
“Genetics, improvements in diagnosis and screening, and the microbiome may also play a role,” says Swanton. “We see them through our clinics and it’s disturbing and we don’t have a good answer as to why this is happening. It is truly a scientific mystery that urgently needs to be solved.”
The increase in premature cases is a global problem. The number of people under 50 affected worldwide has risen by almost 80%, the Guardian reported last year.
A recent review registry data from 44 countries show that the incidence of early-onset cancers is rising rapidly for the intestines and 13 other types, many of which affect the digestive system.
Dr. Aparna Parikh, associate professor of medicine at Harvard Medical School and oncologist at Massachusetts General Hospital, is part of Team Prospect, an international research group funded by Cancer Research UK that is studying the spike in cases.
Speaking at the ASCO conference, she said: “We want to gain a deep mechanistic understanding of biological processes and environmental causes, and to do this we look at a diverse set of data and patients from around the world.”
The boom in cases was complex, Parikh said, but added that it was likely “driven by several factors, including diet, the environment and microbiome characteristics.”
One study presented at the ASCO meeting added to evidence that poor diet was contributing to the rising rates of colon cancer among those under 50.
Ohio State University said the balance between bacteria and inflammation in the gut, both of which are affected by what people eat, could cause “accelerated aging” in the colon.
Swanton said that as researchers rushed to unlock more answers, there were multiple ways people could reduce their risk.
“About four in 10 cases of cancer are preventable, and there are steps people can take to help reduce their risk of cancer,” he said. “Not smoking, maintaining a healthy weight, being safe in the sun and drinking less alcohol all make a big difference.”