Obesity blamed for ‘disturbing’ rise in cancer cases among young
by Cancer cases are rising more quickly in the young than the old because of an obesity epidemic, experts have warned.
The proportion of cases among adults aged 25 to 50 has surged by a quarter in two decades, according to figures, faster than any other age group.
Experts fear the “disturbing” growth in early-onset cancer has been driven by the nation’s unhealthy relationship with food, with obesity rates doubling over the same period.
The number of new cancer cases among Britons aged 25 to 50 has risen to 35,000 each year and the incidence rate, which takes account of population growth, is up by 24 per cent, rising from 132.9 per 100,000 people to 164.6 in 2019, according to the latest data.
The second sharpest rise in cancer rates were seen among the under-25s, where the rate of cancer increased by 16 per cent, from 16.6 cases per 100,000 in 1995 to 19.2 cases.
Among all ages combined the cancer rate grew by 13 per cent, from 539 per 100,000 people to 611.5, which is almost half the rate of the 25-50s.
The slowest rise was among the over-75s, which grew by 10 per cent, from 2,259.7 cases per 100,000 people to 2,482.7 cases, while in those aged 50 to 74, it was up 14 per cent from 955.1 to 1,092.
The analysis by Cancer Research UK (CRUK) comes amid concern that a global epidemic of the disease among the young may be emerging.
Discussing the findings at the American Society of Clinical Oncology (ASCO) conference, scientists said unhealthy diets, a lack of exercise and obesity were likely to be factors behind the surge.
‘Real puzzle’
“Over recent decades, there has been a clear increase in cancer incidence rates in young adults in the UK,” said Prof Charles Swanton, CRUK’s chief clinician.
“We are seeing them through our clinics and it is disturbing and we don’t have a good answer as to why this is happening. It really is a scientific conundrum that urgently needs to be solved. It’s a real puzzle, we’ve got to get to the bottom of it,” he said.
“There are many preventable causes of cancer we know about including smoking, obesity, red meat, but they don’t in themselves explain the increase we’re seeing in the under-50s,” he added. “Bowel cancer is the one that’s the main concern. It speaks to the possibility of there being additional preventable factors that we’re not yet aware of or fully understand.
“There has been a major dietary change in the last 30-40 years. It could be something in the diet that alters the microbiome or something that alters the integrity of the epithelial of the gut. Some people have suggested high fructose corn syrup, other dietary factors that are associated with obesity, or even microplastics and pollutants. We just don’t know.”
He said CRUK had been “thinking about this very hard” and funded the “grand challenge” to research and answer this question.
Two thirds of Britons are either overweight or obese, and almost one in four children aged 10-11 are obese for their age, according to the latest data.
Dr Shivan Sivakumar, associate professor in oncology at the University of Birmingham, said: “We know some of it can be explained by the obesity epidemic in the UK.
“There are also a significant number of patients who do not have obesity who are young and getting cancer [and] other possible reasons can be a modification in their microbiome and also an unknown environmental cause.”
Experts have warned that Britons’ diets are increasingly laden with ultra-processed foods that could be affecting the health of the gut’s microbiome, disrupting the levels of healthy bacteria, which support the immune system and help protect against infection and disease.
‘Accelerated ageing’
One study presented at ASCO by Ohio State University found that an imbalance in bacteria and an increase in inflammation – which can be caused by a diet high in sugar – in the gut caused “accelerated ageing” in the colon, with people under 50 developing bowel cancer cells that appeared to be 15 years older than their real age.
A recent study by the Institute for Fiscal Studies also revealed that there had been a 50 per cent increase in people eating fast food and buying takeaways that has continued since the pandemic caused an increase in their popularity.
The new early-onset figures come months after the Princess of Wales, 41, revealed she was undergoing treatment for cancer, while Dame Deborah James, who founded the charity Bowelbabe, died aged 40 after six years with incurable bowel cancer.
Despite the growing rates of early-onset cancers, they are still uncommon, with about nine in 10 cancers affecting people over the age of 50.
‘Moderate alcohol’
Dr Simon Vincent, director of research at Breast Cancer Now, said young women could ward off the disease by “staying physically active and moderating their alcohol intake”.
The surge in early-onset cases has been seen across the globe with research finding cases among under-50s worldwide had risen 80 per cent in the last three decades.
The number of cancer cases increased from 1.82 million in 1990 to 3.26 million in 2019, while the number of people aged under 50 who died from cancer has grown by 27 per cent.
A recent review of registry records from 44 countries found that the incidence of early-onset cancers was rising rapidly for bowel and 13 other types of cancers, many of which affect the digestive system, and is particularly prevalent among higher-income countries.
Dr Aparna Parikh, an associate professor of medicine at Harvard Medical School and cancer doctor at Massachusetts General Hospital, Boston, is part of an international research effort called Team Prospect, which is aimed at finding answers to the spike in cases.
“We want to gain a deep mechanistic understanding of biological processes and environmental causes,” Dr Parikh told the ASCO conference. “And to do this we’re looking at a diverse set of data and patients from all around the world.”
She said the causes of the surge were “complex”, but likely “driven by various factors, including diet, the environment, and features of the microbiome”.
