Why are so many more young people getting bowel cancer?

While bowel cancer is still rare (one in 14 men and one in 19 women are diagnosed every year in the UK), and 94 per cent of diagnosed people are over the age of 50, one study found that incidence rates in young adults in the US have nearly doubled since the early 1990s, and by 2030 about 15 per cent of all cases will be diagnosed in younger adults.

Its specific increase in the younger adult population is causing many researchers to wonder exactly why so many more young people are being diagnosed with it.

“We don’t yet have a clear answer to what’s causing the rise,” Megan Winter, a spokesperson from Cancer Research UK (CRUK) tells us. “Population growth accounts for part of it but preventable risk factors, genetics and improvements to early detection could also play a role.”

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In-depth research statistics by CRUK found that over half of bowel cancer cases in the UK are preventable, with 28 per cent of cases being caused by eating too little fibre, 13 per cent by eating too much processed meat, 13 per cent caused by drinking alcohol and smoking, and 11 per cent caused by obesity.

“Key factors that contribute to the rise in bowel cancer rates among young people include being overweight, obesity and related health conditions, such as high blood sugar levels and diabetes,” confirms Professor Carlo La Vecchia, one of the lead researchers behind the 2023 study in Annals of Oncology. “Additional reasons are increases in heavier alcohol drinking over time in central and northern Europe and the UK, and reductions in physical activity.”

What could be causing the rise in bowel cancer in young people?

While there’s not a definitive confirmation on what could be causing the rising cases of bowel cancer in young adults (and researchers are still actively looking into it), genetics, along with lifestyle, can both be contributors.

“It's not always known what causes bowel cancer, but it can be caused by genetic changes if you have it running in the family, as well as lifestyle and environmental factors,” says GP Dr Nabeel Arshad from The Brooke Surgery in Greater Manchester. “Certain health conditions can make it more likely to get bowel cancer: for instance an underlying inflammatory bowel disease (IBD) such as Crohn's or ulcerative colitis, can sometimes predispose you to cancer, but it is not guaranteed and it’s important to understand it just increases your likelihood. Also key factors are if you're over 50, if you smoke, if you're overweight, and if you have a very close relative that has bowel cancer.”

Diet

A leading suspect in the rise of bowel cancer cases is our diet. The so-called 'Western diet', characterised by a high consumption of red and processed meat, sugary drinks and a lower intake of fibre, fruits and vegetables, is widely believed to increase your bowel cancer risk. In fact, back in 2015 the World Health Organisation (WHO) classified processed meats (things like bacon, sausages and deli meat) as a Group 1 carcinogen, meaning it is known to cause cancer in humans. Red meat is less strongly linked, and is classified as Group 2A carcinogen but as a rule of thumb, we should be eating no more than about three portions a week, equivalent to 500g. With more young people consuming fast food in the modern diet, rich in processed and red meat, this dietary change could be a key contributor.

Additionally, a diet that’s low in fibre is also believed to play a role. Fibre is crucial in maintaining a healthy digestive system because it promotes regular bowel movements and supports a diverse gut microbiome. Diets high in fibre from fruits, vegetables and wholegrains are associated with a reduced risk of bowel cancer, which a modern diet is often lacking.

A balanced diet is important to manage weight, and should include lots of protein, high fibre, starchy foods, plenty of fruit and veg and healthy fats. Quitting smoking and decreasing your consumption of alcohol can also lower the risk of not just bowel cancer, but many others, too.

Sedentary lifestyle

Obesity rates have also risen dramatically, and excess body fat (particularly visceral fat – the fat that surrounds your internal organs) can cause chronic inflammation and insulin resistance which can contribute to your cancer risk.

A lot of this is down to not just diet but the fact we’re all living more sedentary lifestyles, partly thanks to deskbound jobs and sitting in front of screens. Young people especially engage far more in prolonged sitting and limited physical activity. A lack of exercise has been associated with a higher risk of developing bowel cancer because regular physical activity helps regulate weight, reduce inflammation and maintain a healthy bowel function.

The NHS recommends adults do strengthening activities at least two days a week, alongside at least 150 minutes of moderate intensity activity a week. Across five days, that’s only a 15-minute brisk walk every day.

Gut microbiome imbalance

We’re a generation obsessed with gut health, and for good reason. The gut microbiome, which consists of trillions of bacteria, plays a key role in digestion, immune function, and maintaining gut health. A healthy, balanced microbiome helps regulate the immune system, protect the intestinal lining, and reduce inflammation. However, disruptions in the gut microbiome, a condition known as dysbiosis, can contribute to cancer development, including bowel cancer.

The modern lifestyle, characterised by poor dietary choices, frequent use of antibiotics, and limited exposure to beneficial bacteria due to overly sterile environments, may be contributing to dysbiosis in younger individuals. This microbial imbalance may be a key factor in the rising rates of bowel cancer among young people. You can support your gut health in many ways, the biggest being consuming a high-fibre diet, including lots of fermented foods such as yogurt, kefir, sauerkraut and kimchi.

Screening gaps

One of the challenges with early-onset bowel cancer is that younger individuals are not typically offered routine colorectal cancer screenings, which are generally recommended for people over 50. As a result, symptoms can be overlooked or misattributed, and younger patients are often diagnosed at later stages when the cancer is more advanced and harder to treat.

Raising awareness of the symptoms of bowel cancer and the need for earlier screening in high-risk populations could improve early detection and outcomes. This is why it’s so important to understand the symptoms and ask for a screening with your GP if you’re concerned.

“If your doctor is suspecting bowel cancer, they would likely perform an examination,” explains Dr Arshad. “This would mean a feel of your tummy, then possibly a rectal examination wearing a plastic glove with some lubrication and passing a finger into the back passage. For stool assessment, they could consider a stool sample for a special test called a faecal immunochemical test (FIT). They might even do your blood test looking for anaemia, as there's a suspicion for bowel cancer when it’s present.”

What bowel cancer symptoms should we be looking out for?

For Amy, it was blood in her stools that was the first time she realised something could be wrong, along with changes in the frequency and urgency of her bowel habits. It was realising she was rapidly losing weight that prompted her to see her GP.

“I put a lot of these symptoms down to being pregnant, and then being a new mother – things like blood in the stools I thought could perhaps be haemorrhoids,” she says. “The frequency and urgency that I needed to go, it got to the point I was going 10 times a day.”

Changes in your bowel habits is the first thing to look for, according to Dr Ashad. “Firstly, it could be change in the consistency of your stools – you might find you’re having harder stools that’s not normal for you, or it could be suddenly having loose stools. Along with the actual consistency of the stools, it can be the frequency. So, if you're going a lot more often, or you're going less often, and it doesn't have to be constipation for it to be going less often.”

Another big thing to be aware of is blood in your poo, along with bleeding from your bottom that’s not associated to haemorrhoids or an anal fissure. “So, blood in the bowels coming into the stools can either be fresh red if it's coming from lower down in the bowel, but if it’s higher in the bowel, your stools can look black. Now be mindful that having lots of spinach or iron tablets can also make it black,” Dr Ashad explains.

Other symptoms can include:

Tenesmus – the sensation that you need to poo, but you might have just gone to the toilet
Abdominal pain, including lumps in the abdomen, or sudden bloating
Losing weight without trying
Feeling tired for no reason

“Yet bowel cancer can also be silent,” adds Dr Ashad. “Sometimes you might not have any sign of symptoms. You might not see blood, but you're just feeling tired suddenly, as cancer can cause anaemia. If it's just the odd day or one off, then it's unlikely to be of any significance, but if you have any of these symptoms of bowel cancer for three weeks or more, then you should see a GP.”

The rise of bowel cancer in young people is complex. While changes, such as the modern diet, poor gut health, increased obesity and sedentary lifestyles appear to be a driving trend, genetics and the lack of early screening further complicate the picture. Researchers are continuing to investigate the phenomenon, while charities such as Bowel Cancer UK continue with campaigns like Never Too Young in a bid to educate and support young people in receiving a proper diagnosis.

Amy’s story

“I was pregnant when I started thinking something was a bit off, but the symptoms could also have been explained by being pregnant. I kept telling myself that my GP would think so too, and just assumed once I gave birth they would probably stop. It was blood in my stools that I first noticed, and then needing to go more frequently and more urgently.

Then I gave birth, and it was a whirlwind of six months being a new mum, and the blood was still in my poo, but I put it down to haemorrhoids because I birthed a big baby, and was sitting down much, much more. But it got worse, and the frequency and urgency increased, and I don’t know what prompted me to do it, but I took my dog to the vet and stood on the scales and weighed myself. This was on New Year’s Eve 2022, then six days later I thought I felt like I was losing a lot of weight despite not trying to and weighed myself again and I was over half a stone lighter.

I called my GP and got an appointment almost immediately. I went in and they gave me a thorough examination and then referred me straight away under the ‘two-week rule’ – this is something that ensures patients with symptoms or test results that may indicate cancer are seen by a specialist within two weeks. I was also given a faecal immunochemical test (FIT), which is currently only available to those aged 54 to 74 years, unless like me, you’re showing worrying symptoms.

It was an easy test that can tell you whether you might have bowel cancer, or an autoimmune disease, or there’s nothing wrong. I remember missing a phone call and listening back to a voicemail from my GP saying she needed to speak to me about my results. I knew it was bad news, and when she rang me back and confirmed my results were ‘off the scale’, I couldn’t quite believe it, but also, I could.

I went and saw a consultant who at first told me he was going to do a polypectomy (a simpler surgical procedure), but then given my age and the fact I had a young child, and that the tumour was quite big, he didn’t want to risk leaving any behind. So instead, he suggested a bowel resection and that’s what I had. I remember the first time I did a poo after surgery; I was literally dancing back into the ward. They removed part of my bowel, and resewed it back together, and removed 20 lymph nodes, 10 of which were showing signs of cancer.

Last summer felt like a blur, I was having surgery and chemotherapy, I couldn’t hold my daughter for six weeks and I had to stop breastfeeding early to have surgery. But they got it all out, and I’m now in remission with the hope I’ll get the official all-clear after five years. I was lucky that my doctor took it so seriously, but since joining a support forum as part of Bowel Cancer UK, I’ve spoken to a lot of young people who had to really push their GP. Also, I get it, talking about poo, and the thought of someone examining up there can be embarrassing and scary, but the alternative is a lot scarier.”

Why are so many more young people getting bowel cancer?

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