There has been an undeniable but (so far) inexplicable rise in colorectal — or bowel — cancer among younger people. Potential explanations involving E. coli and unprocessed food have been put forward, but as of yet, there is no definitive cause.
Now, researchers at the Institute of Cancer Research (ICR) in the U.K. are turning to 70-year-old tumor samples stashed in the basement of a London hospital in the hope of solving the mystery.
“People in the 1960s lived differently to people today,” Trevor Graham, Professor of Genomics and Evolution and Director of the Centre for Evolution and Cancer at The ICR, said in a statement.
“We believe that the exposome — the changes in diet, lifestyle, and environmental factors we are exposed to — is contributing to the increase in cases and deaths from bowel cancers in younger adults.”
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The Boomers Project
The study is being referred to as the “Boomers Project” and will involve trawling through a vast collection of colorectal cancer samples stored at St Mark’s Hospital, which has thousands of specimens, some dating to the 1930s. Tests have shown that, despite their age, these samples are remarkably well preserved.
By comparing the specimens with modern samples, the team aims to determine what changes in diet, lifestyle, and the environment may be behind the surge in cases. Specifically, the researchers plan to use genome sequencing and advanced molecular analysis techniques.
The hope is that this will allow scientists to find out how various environmental exposures, from diet to pollutants, have modified DNA in each of the samples — and how these exposures have shifted over time. The team is particularly interested in changes to the gut microbiome, the bacteria found in the bowel.
“We don’t yet know whether it’s one factor or many, ranging from diet and genetics to microplastics and sedentary lifestyles,” Kevin Monahan, Gastroenterologist and Co-Director of the St Mark’s Centre for Familial Intestinal Cancer, said in a statement.
“What’s striking is that many younger patients show no obvious signs of poor health yet are being diagnosed with aggressive forms of bowel cancer.”
Bowel Cancer Cases Rise Around the World
Practitioners across much of the world have noticed an alarming trend in recent years: while bowel cancer is more common in older adults, there has been a steady uptick in the number of cases reported in those aged 54 and younger. According to the American Cancer Society, the increase equates to 2 percent a year. In contrast, incidence in those aged 65 and older has declined.
This meant that, in 2019, 1 in 5 patients diagnosed with bowel cancer in the U.S. were aged 54 or younger — double that reported in 1995. Similar patterns have been documented in the U.K., Canada, and many other countries worldwide.
According to the ICR, early-onset cases such as these tend to be diagnosed later and appear to act more aggressively than those in older people — a situation that can result in poorer outcomes.
What Could Be Behind The Surge In Cancer Diagnosis?
There have been various explanations put forward to account for this troubling trend, from a sedentary lifestyle to ultraprocessed food to microplastics, according to studies in Cancer Epidemiology, JAMA Oncology, and JNCI Cancer Spectrum. There are even suggestions that the rise, which, according to a study in the Journal of the National Cancer Institute, first began in the 1960s, is linked to exposure to a specific type of E. coli in childhood.
But so far, there is not enough evidence to say with a high level of certainty that the increase in bowel cancer among younger people is related to any one factor. This is something researchers at the ICR hope to change.
“We believe that our unique resource of historical tumour samples at St Mark's Hospital will open a window to new approaches to [the] prevention of bowel cancer in the young,” said Monohan.
This article is not offering medical advice and should be used for informational purposes only.
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