by Last year, speakers at the annual meeting of the American Society of Clinical Oncology – the world’s most prestigious cancer conference – sounded a stark warning.
Colorectal cancer rates were increasing rapidly among the under-40s, they said, so much so that cases in this age group are expected to double by 2030, and the disease will be the first source of cancer deaths between 20 and 49 years of age. year old by the end of the decade.
“Studies are showing this increase in early-onset colorectal cancer,” says Dr Dimitra Lamprinaki, a researcher at the Quadram Institute in Norwich. “The problem is that some of these cases are asymptomatic but also young people may ignore signs of cancer that may progress and be difficult to remove.”
This is part of a general trend. Global cancer cases in the under-50s are increasing rapidly, increasing by 79 percent between 1990 and 2019 according to recent research. But while lifestyle factors, such as highly processed diets and heavy alcohol use in the millennial generation, are likely to blame, scientists have discovered an important new link – microbes that fuel these bad habits and fuel more aggressive cancers and are more resistant to treatment.
These are some of the main factors that may be causing increased rates of cancer cases among young people.
Vaping and poor oral hygiene
London-based private clinic Pure Periodontics has seen an alarming rise in gum disease in younger patients. They attribute this to diets loaded with sugar and acids as well as the rise of vaping in people under the age of 40, a habit that blocks blood flow to the gums, increasing susceptibility to infections. and making healing more difficult.
All this promotes the growth of a certain strain of bacteria called Fusobacterium nucleatum (F. nucleatum) associated with a whole range of cancers including breast, colorectal and head and neck cancer.
“It’s a very sticky bug that sticks to the surface of the teeth and gums, and allows other harmful bacteria to enter,” says Dr Tim O’Brien, medical oncologist and researcher at Queen’s University, Belfast.
With poorer oral hygiene, these bacteria can multiply, enter the bloodstream, and gain access to various organs. When these microbes enter early-stage tumors, they can actively interfere with chemotherapy and radiotherapy, enabling the cancer to grow and spread.
“Fusobacterium can contribute to chemotherapy but also resistance to radiation,” says O’Brien. “It thrives within the tumor environment so it is in the interest of the tumor to survive. So it interferes with the process by which chemotherapy self-destructs cancer cells and can also kill immune cells that are trying to destroy the tumor.”
High intake of processed meat
According to the journal Nature, stomach cancer is one of the sharpest increases in cancer rates among people under the age of 50.
One of the most well-known risk factors for stomach cancer is the bacteria Helicobacter pylori (H. pylori) which is thought to be responsible for around 40 per cent of cases in the UK. H. pylori lives in the mucous layers that line the stomach and contributes to conditions such as atrophic gastritis, the chronic inflammation and thinning of the stomach lining, which can then progress to cancer.
Research has shown that a diet high in processed meats such as sausages, bacon and hamburgers can reduce the prevalence of H. pylori in the stomach.
Professor Andrew Beggs, Consultant Colorectal Surgeon at the University of Birmingham, describes the connection between such microbes and lifestyle factors as ‘crucial pieces of the puzzle’.
“You have these bacteria and you have an unhealthy lifestyle with excess red meat, alcohol, and smoking, and some people may have a genetic predisposition that increases their risk,” he says. “When you add all of those factors up, the risk of cancer increases dramatically.”
Oral sex
Not only the bacteria can drive cases of cancer, viruses are also linked to different types of the disease. Specialists across the UK have described rising rates of oral cancer particularly in people aged 40 to 49, with half of these cases linked to a strain of the sexually transmitted human papillomavirus (HPV), which called HPV-16 which can be passed. through oral sex.
One possibility could be a greater number of casual sex partners, with a study in the journal Cancer finding that kissing and particularly deep kissing is linked to an increased risk, with individuals who had 10 or more deep kissing partners twice as likely to develop VSD. -related to cancer.
Ultra-processed foods
The IS F. nucleus bacteria not only make cancers more resistant to treatment, but can actively drive the disease, especially in the gut. A new study i nature published last week, found that mice given a specific subspecies of this bacterium developed pre-cancerous intestinal growth and accelerated tumor formation compared to normal mice.
Researchers have studied this bacterium as well as certain species of it E.coli who have also been linked to colorectal cancer, they believe that a diet high in ultra-processed foods can alter the composition of the microbiome in the gut in a way that enables these species to flourish, increasing the risk of cancer developing through several mechanisms.
“Some bacteria enable gut cells to acquire stem cell-like properties, increasing the chance of cancer formation at the cellular level,” says Dr Meera Patel, a researcher in the Colorectal & Peritoneal Oncology Laboratory at the University of Manchester.
“There is also a theory that certain bacteria can weaken the vascular barrier of the gut which stops the spread of bacteria from your colon to your wider circulation, and if you have a weakened vascular barrier, tumor cells can move out of the colon and metastasize to. other organs.”
Excessive alcohol
However, there are other cases of cancer among the young where a microbial involvement has not yet been identified.
For example, testicular cancer is the most commonly diagnosed solid tumor cancer in young men, and according to the NHS, the number of cases identified each year in the UK has doubled since the 1970s for reasons that specialists cancer still trying to do. understanding.
Family history is one of the biggest risk factors for this type of cancer, but some population studies have also identified a link between excessive drinking and a form of the disease called testicular germ cell carcinoma.
Young men who drank 14 or more alcoholic drinks per week were found to be at greater risk, along with a diet high in fat, red meat and dairy products as well as low in fruit and vegetables.
New treatments
However, the emerging link between microbes and different types of early-onset cancer in young people could lead to new targeted treatments, such as phage therapy involving specially engineered viruses have to give the patient programmed to feed a particular species of problematic bacteria, or targeted vaccines.
“You could vaccinate mice before you adopt them F. nucleus and see if it makes a difference in terms of their outcomes on polyps and cancer,” says Beggs. “If that’s the case, there will be a strong argument for a phase one trial in humans to see if it reduces the incidence of colorectal cancer.”
O’Brien predicts that in the coming years, the particular microbial composition of a tumor may be used to determine treatment decisions.
“We don’t use that information right now, but in the future, I think we’ll be able to get that and use it to decide if this is a very aggressive tumor, and if a higher dose The patient needs chemotherapy,” he says.
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