Wave of colon cancers in young people may be fueled by surprising factor linked to mental health

Stress and anxiety may partly explain why colon cancers are surging in younger generations of Americans, a study suggests.

Researchers from the Sichuan University of China found that when under frequent stress, a number of healthy bacteria that live in the gut start dying off, making it easier for cancer to move in.

When these bacteria die off, tumors grow more quickly, they found, leading to more aggressive, rapidly growing colorectal cancers. 

These findings come amid an uptick in colon and rectal cancers in young people in the US and UK – which experts have previously attributed to diet. 

Data from JAMA Surgery showed colon cancer is expected to rise by 90 percent in people ages 20 to 34 by 2030

However, an emerging area of science suggests the body’s gut and microbiome may play a role. 

At the same time, data shows more young Americans and Brits than ever are constantly stressed, anxious or depressed. Polls have consistently shown younger generations are more stressed than any other demographic. 

A 2023 survey from the American Psychological Association found that the average 18 to 34 year old rates their stress level at a six out of ten, whereas people 65 and above rate their stress slightly above a three. 

The US has the sixth highest rate of early-onset cancers – 87 cases per 100,000 people – and colorectal cancers (CRCs) are among the fastest rising.

Diagnoses among people under 50 years old, which are classified as early-onset, are expected to rise by 90 percent in people 20 to 34 years old from 2010 to 2030.

A number of factors have been under suspicion of causing the rise of the disease in young people – a diet of highly processed foods and energy drinks, obesity, a disruption in the beneficial bacteria in the gut and more recently, high blood sugar. 

Overusing antibiotics has also been posited as a factor, but a separate study in the journal Clinical Gastroenterology and Hepatology, found the research examining this link have reported conflicting findings and newer results were not statistically significant.

When taken sparingly, antibiotics are highly effective, safe treatments for bacterial illnesses and these medications have revolutionized how doctors fight infection.  

But when taken too frequently, they can cause a major disruption in the healthy colonies of bacteria that live in the gut – the body’s microbiome.

The team from China therefore used an antibiotic cocktail to test their theory. 

The research was presented at the United European Gastroenterology Week 2024, but has yet to be published in a journal or peer reviewed, meaning full details of the study – carried out with mice – are not known.

Lead researcher Dr Qing Li said: ‘In our study, we used an antibiotic cocktail to eradicate gut microbiota, followed by fecal microbiota transplantation to investigate whether gut microbiota was necessary for chronic stress to accelerate CRC progression.’

Fecal microbiota transplantation is a scientific term that means researchers transferred healthy poop into the body of someone with an unhealthy gut, with the aim of repopulating their GI tract with healthy bacteria.  

They supplemented mice who had CRC with a healthy poop sample, exposed those mice to stress and watched what happened to their cancer progression. 

The Lactobacillus plantarum bacteria lives naturally on the gut and in some fermented foods. Researchers found that when they were absent from the gut cells, tumors grew more easily

In another group of mice with CRC, they introduced antibiotics to kill off the bacteria in the gut, and exposed the animals to stress. 

In mice without any gut bacteria, tumors grew faster than when they had a robust microbiome to protect them.

In addition, even when antibiotics weren’t introduced into the system, researchers showed stress alone can dampen the microbiome, making the body more susceptible to tumors.

Stress alone, therefore, could make colorectal cancer and tumors more likely, the study authors suggest. 

One group of bacteria in particular seemed to be especially affected by antibiotics and stress: lactobacillus. 

Older research from Trinity College in Ireland has suggested these bacteria support the body’s immune system, can protect against virus and bacteria and prevent damage in gut cells. 

This bacteria is found naturally in many fermented foods and in the human body. When the body was exposed to antibiotics, the lactobacillus was completely depleted in both groups tested. 

Dr Li said: ‘This depletion highlights its crucial role in maintaining gut health and its potential association with CRC progression under chronic stress.

‘Restoring beneficial bacteria in the gut, such as Lactobacillus, could strengthen the body’s natural defenses against colorectal cancer.’ 

Doctors might be able to harness Lactobacillus in the future to treat CRC cancer, Dr Li suggested.  

The above shows the symptoms and their frequency in early onset patients, who develop colon cancer before the age 50 years, and late onset, who develop the cancer after this age

There are an estimated 100trillion bacteria that live in and around the digestive tract – more than the number of cells in the body- according to research from Emory University. 

They help keep the area lubricated, assist the body in breaking down food and can even manufacture neurotransmitters and vitamins the body needs to function. 

The University of Missouri-Kansas City research found rate of colorectal cancers grew 500 percent among children ages 10 to 14 and 333 percent among teenagers 15 to 19 years old.

Rates rose by 71 percent among people 30 to 34 to seven cases per 100,000 people. And among people 35 to 39, rates rose by 58 percent to 12 cases per 100,000 people.

Rates of colorectal cancer in people 10 to 44 years old have risen in all age groups.

The rate of colorectal cancers grew 500 percent among children ages 10 to 14 and 333 percent among teenagers 15 to 19 years old.

Rates rose by 71 percent among people 30 to 34 to seven cases per 100,000 people. And among people 35 to 39, rates rose by 58 percent to 12 cases per 100,000 people.