Rising obesity rates suspected in surge of cancer in under-50s in the UK

Cancer rates for people aged 25 to 49 are expected to rise from 32,600 a year to 34,000 by 2040

Changes to lifestyles and diets and rising obesity rates have an impact on cancer rates in the UK, experts say. Getty Images

Rising rates of obesity could be behind a surge in cancer cases in adults under the age of 50 in the UK, experts have said.

Between the early 1990s and 2019, the number of cases of cancer in people aged 25 to 49 rose by 24 per cent – more than any other age group, and more than twice the 10 per cent increase reported in over-75s.

Cases among those aged 25 to 49 rose from 132.9 per 100,000 people in 1993 to 164.6 by 2019.

The second largest increase was in the under-25s, with a 16 per cent rise, from 16.6 cases per 100,000 to 19.2.

The lowest increase was reported in the over-75s group. On average, the cancer rate increased by 13 per cent, from 539 in every 100,000 people to 611.5.

Cancer rates are expected to keep increasing, rising to 34,000 a year for people aged 25 to 49 by 2040. They are currently about 32,600 a year.

Experts said the increase could be related to unknown risks, genetics and improvements in diagnosis and screening.

But they suspect changes to lifestyles and diets and rising obesity rates may also have played a role.

“Over recent decades, there has been a clear increase in cancer incidence rates in young adults in the UK,” said Prof Charles Swanton, chief clinician at Cancer Research UK.

“Evidence suggests that more adults under 50 may be getting cancer than before. Although these cases are a small proportion of the overall population and still relatively uncommon, the trend is important, and it requires further investigation.

“Increased exposure to known as well as unknown cancer risk factors, changes to lifestyles and diets over time, and rising obesity may all contribute to the uptick in early-onset cancer. Genetics, improvements in diagnosis and screening and the microbiome could also play a role.”

About 25 per cent of adults in England are obese, according to the Health Survey for England 2021. A further 38 per cent are overweight but not obese.

About four in 10 cancer cases are preventable, said Prof Swanton. There are steps people can take to cut risk, such as not smoking, keeping a healthy weight, staying safe in the sun and cutting alcohol consumption.

The problem does not only affect the UK, with cancer cases rising in young people globally.

Team Prospect, an international research organisation which is funded by several institutes, including Cancer Research UK, has been given the responsibility of determining why these changes are happening.

Dr Aparna Parikh, an oncologist and member of Team Prospect, said: “Team Prospect is seeking to understand what is driving a global, stark rise in early-onset colorectal cancer.

“We want to gain a deep mechanistic understanding of biological processes and environmental causes, and to do this we’re looking at a diverse set of data and patients from all around the world.

“This is complex, and the rise in early-onset colorectal cancer cases is driven by various factors, including diet, the environment, and features of the microbiome [micro organisms].

“A greater understanding of why cancer cases are rising can help us to understand how to intervene and identify high risk patients for cancer screening. By trialling methods to assess risk and prevent early-onset colorectal cancers, we can shape a hopeful and healthier future for younger generations.”

A study released last year found that obesity is linked to an increased risk of cancer, with the risk varying by gender and type of illness.

The study, published in the Cancer Cell journal, discovered that all cancer types, except brain, cervical, and testicular cancers, are associated with at least one obesity-related trait. The results also showed gender-specific associations.

In female patients, the strongest links between overall fat accumulation and cancer were in gallbladder cancer, endometrial cancer, and oesophageal adenocarcinoma.

For men, the strongest links were in breast cancer, hepatocellular carcinoma, and renal cell carcinoma.