The hunt is on to learn why bowel cancer in young people is rising

One of the most worrying cancer trends is the rising incidence of many types of tumors in people under 50, especially bowel cancer.

Now a £20m, five-year research project has been approved to find out why bowel cancer cases are rising. It will use blood, urine and stool samples from millions of people from about 15 biobanks in Europe, North America and India.

The goal is to understand whether this rise is related to changes in food, drinks, drugs, air pollutants or other environmental chemicals by measuring everything people are exposed to, called the “exposome.”

“The exposome is all the elements of our external world that have an impact on our health,” says Andrew Chen at Massachusetts General Hospital in Boston, co-director of the project.

The number of people under 50 being diagnosed with bowel cancer has been increasing for three decades. In the UK, for example, such tumors have increased by about 50% in people aged 25 to 49 during this period, with similar trends seen in the United States, Canada, Australia and several European countries.

Since about nine out of 10 tumors occur in older people, the increase in people under 50 has not yet had a big impact on the total number of cancer deaths. But the trend has doctors concerned, especially because tumors in younger people can be more aggressive and are often diagnosed at later stages.

There has been much speculation as to the cause, with the main suspects being aspects of the modern diet – such as our increased consumption of processed foods or red meat, or a lack of fiber – as well as antibiotic use or exposure to pollutants.

in new research projectsChen and his team will investigate further by trying to identify and measure all the chemicals in the medical samples from previous studies.

They will use mass spectrometry to identify chemical signatures of novel compounds that have entered the body or disturbances in the levels of natural biochemicals.

One of the biobanks being used is the Nurses’ Health Study 3, a large US project that charts the health and lifestyles of hundreds of thousands of nurses. A subset of participants donated stool samples and blood samples, which will also allow the research team to analyze their gut bacteria.

Another important cohort is the Danish Newborn Screening Biobank, which contains dried blood spots from almost all babies born in Denmark since 1982, with nearly 2 million samples. This will allow researchers to see if anything we are exposed to in the womb is linked to a higher risk of bowel cancer.

If, as hoped, a correlation emerges between certain biochemicals in the blood and bowel cancer risk, the team will investigate whether blood tests can identify people who are more vulnerable, Chen said. “This may be the group we target for more intensive bowel cancer screening,” he said.

Another part of the project will test whether a targeted diet can reverse blood and gut bacterial signatures linked to bowel cancer risk. Jordana Bell A professor at King’s College London and one of Chen’s collaborators. “We will try to apply these insights we generated earlier by identifying putative causal factors, understanding underlying mechanisms and designing intervention trials,” she said.

Iain Foulkes, from Cancer Research UK (CRUK), said: “In the US, the latest figures show that people born in the 1990s have a 2.4 times greater risk of colon cancer than people born in the 1950s. Most cancer cases occur in people over the age of 50, but this development is an important issue we need to address. The key is to understand why early-onset cancers are increasing in the first place.”

CRUK funded the work together with the National Cancer Institute in Maryland, the National Cancer Institute in France and the Bowelbabe Foundation in the UK.