Early-onset colon cancer: the surge no one can explain with a single cause
Early-onset colorectal cancer cases are rising in 27 countries. In Spain, young people are the hardest hit. Hypotheses include diet, microplastics and bacterial toxins.
English · Original discussion in Spanish · Published
Colon cancer is surging among 25 to 49-year-olds: cases are growing in 27 of 50 countries, and in 20 of them the increase is exclusive to young people or far faster than in adults
A study published in The Lancet with data up to 2017 detected a global trend that was already worrying at the time. Early-onset colorectal cancer (between 25 and 49) is increasing in 27 of the 50 countries analysed. But the most revealing finding is that in 20 of those 27 territories, the increase is exclusive to young people or advancing much faster than in the adult population. Spain is no exception: figures from the INE (national statistics institute) and REDECAN (the Spanish cancer records network) point to a curve that is worrying oncologists.
The competing hypotheses: from red meat to mRNA vaccines
The debate over the causes has become polarised. On one side, the official narrative insists on classic factors: a diet rich in red and processed meat, alcohol, low-quality tobacco (young people smoke less but with a higher toxic content), sedentary lifestyles and obesity. However, many point out that today's diet is not so different from that of previous generations as to explain such a sharp jump. Moreover, red meat consumption in Spain has fallen over the past decade.
On the other side, one current points to the messenger RNA vaccines administered en masse during the pandemic. It is argued that spike proteins could interfere with the p53 tumour suppressor protein, and that the rise in cancers among young people —the least vaccinated cohort in some countries— contradicts that hypothesis. But vaccination data in Spain show that 20 to 29-year-olds had rates above 90%, which weakens the argument that they are the least vaccinated group.
Johns Hopkins' 'missing link': a bacterial toxin
In May 2026, researchers at Johns Hopkins' Kimmel Cancer Center announced the discovery of the 'missing link' in the development of early-onset colorectal cancer. They identified a toxin produced by a bacterium (Escherichia coli carrying the pks gene) that damages the DNA of intestinal cells. The hypothesis is that exposure to this bacterium in childhood, combined with other factors such as diet or antibiotic use, could be behind the rise in young people. The finding opens a new avenue, but there is still no certainty.
Microplastics, additives and pollution: the chemical cocktail
Another line of research points to the accumulation of microplastics and food additives (emulsifiers, sweeteners, preservatives) that have become widespread over the last 20 years. Exposure to these compounds could alter the gut microbiome and the mucosal barrier, facilitating cellular damage. The list of suspects ranges from dark-roasted coffee to antibiotics in meat, including industrial pollutants.
But all these hypotheses run into an obstacle: epidemiological studies covering the period after 2020 are not yet complete. The most solid data (The Lancet, 2017) predates the pandemic, so it cannot assess the effect of vaccines or lockdowns. REDECAN's records and other official sources lag by 2 to 3 years, making real-time analysis difficult.
All in all, the consensus is that there is no single cause, but a perfect storm: ultra-processed diets, antibiotics, pollution and, perhaps, iatrogenic factors. While science catches up, young Spaniards watch as colon cancer, once a disease of the elderly, creeps into their lives. What if the answers lie in the childhood of those now in their 30s?
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A study published in The Lancet with data up to 2017 detected a global trend that was already worrying at the time. Early-onset colorectal cancer (between 25 and 49) is increasing in 27 of the 50 countries analysed. But the most revealing finding is that in 20 of those 27 territories, the increase is exclusive to young people or advancing much faster than in the adult population. Spain is no exception: figures from the INE (national statistics institute) and REDECAN (the Spanish cancer records network) point to a curve that is worrying oncologists.
The competing hypotheses: from red meat to mRNA vaccines
The debate over the causes has become polarised. On one side, the official narrative insists on classic factors: a diet rich in red and processed meat, alcohol, low-quality tobacco (young people smoke less but with a higher toxic content), sedentary lifestyles and obesity. However, many point out that today's diet is not so different from that of previous generations as to explain such a sharp jump. Moreover, red meat consumption in Spain has fallen over the past decade.
On the other side, one current points to the messenger RNA vaccines administered en masse during the pandemic. It is argued that spike proteins could interfere with the p53 tumour suppressor protein, and that the rise in cancers among young people —the least vaccinated cohort in some countries— contradicts that hypothesis. But vaccination data in Spain show that 20 to 29-year-olds had rates above 90%, which weakens the argument that they are the least vaccinated group.
Johns Hopkins' 'missing link': a bacterial toxin
In May 2026, researchers at Johns Hopkins' Kimmel Cancer Center announced the discovery of the 'missing link' in the development of early-onset colorectal cancer. They identified a toxin produced by a bacterium (Escherichia coli carrying the pks gene) that damages the DNA of intestinal cells. The hypothesis is that exposure to this bacterium in childhood, combined with other factors such as diet or antibiotic use, could be behind the rise in young people. The finding opens a new avenue, but there is still no certainty.
Microplastics, additives and pollution: the chemical cocktail
Another line of research points to the accumulation of microplastics and food additives (emulsifiers, sweeteners, preservatives) that have become widespread over the last 20 years. Exposure to these compounds could alter the gut microbiome and the mucosal barrier, facilitating cellular damage. The list of suspects ranges from dark-roasted coffee to antibiotics in meat, including industrial pollutants.
But all these hypotheses run into an obstacle: epidemiological studies covering the period after 2020 are not yet complete. The most solid data (The Lancet, 2017) predates the pandemic, so it cannot assess the effect of vaccines or lockdowns. REDECAN's records and other official sources lag by 2 to 3 years, making real-time analysis difficult.
All in all, the consensus is that there is no single cause, but a perfect storm: ultra-processed diets, antibiotics, pollution and, perhaps, iatrogenic factors. While science catches up, young Spaniards watch as colon cancer, once a disease of the elderly, creeps into their lives. What if the answers lie in the childhood of those now in their 30s?
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Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (89 replies).
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