Young cancer patients are no longer uncommon. (symbol image)Image: imago
The latest figures from the Federal Statistical Office show: The millennial generation is significantly more likely to suffer from cancer than their peers did thirty years ago. Researchers are struggling for explanations.
November 30, 2025, 05:53November 30, 2025, 05:53
Stephanie Schnydrig / ch media
It is one of the great unsolved mysteries of medicine: Why are more and more young people getting cancer? What was first noticed in the USA in the 1980s is evident worldwide today – and according to the new national cancer statistics also in Switzerland. The number of cancer cases among young adults in this country has been rising steadily since the 1990s.
Millennials, those aged 25 to 39, are the most affected. Their cancer rate has increased by a good 14 percent since the mid-1990s.
Image: chmedia
The trend is particularly clear when you look at individual diagnoses: breast cancer, by far the most common type of cancer in women, rose by around 60 percent in this age group. The increase was even greater for colon cancer (+137 percent) and thyroid cancer (+94 percent).
Image: chmedia
Testicular cancer remains the most common diagnosis in men, with the number of cases increasing by 14 percent. However, colon cancer (+142 percent) and thyroid cancer (+101 percent) are also increasing significantly.
“While young adults with cancer were considered isolated cases ten to twenty years ago, we unfortunately see them more and more frequently today,” says Sacha Rothschild, head of oncology at the Baden Cantonal Hospital and vice president of the Swiss Cancer Institute.
He admits that part of the increase is certainly due to improved diagnostics: “Today, incidental findings are often discovered through imaging procedures such as CT examinations. Most of them are harmless and would never develop into a malignant tumor – but when you see something, you act. And that’s a good thing.”
Thanks to early detection and improved treatment options with new drugs as well as therapies optimized through clinical cancer research, fewer young people are dying of cancer despite the increasing number of diagnoses. Today in Switzerland there are around 7.5 deaths per 100,000 people between the ages of 25 and 39; a total of about 136 people per year. In the mid-1990s it was still 13.2 per 100,000, i.e. around 227 deaths.
Image: chmedia
Although the decline is considerable, it would probably be significantly greater if the number of new cases were not increasing at the same time – an increase that cannot be explained by previously overlooked cases, but is real.
A web of causes
A research team led by geneticist Alberto Bardelli from the University of Turin set out to search for clues. In the journal “Cell Reports Medicine” It describes what may have changed in the last few decades and what developments are driving the wave of early cancer cases.
“Westernization” of nutrition
Fast food, ready meals and highly processed products contain numerous potentially carcinogenic substances – such as nitrosamines, polycyclic aromatic hydrocarbons or the chemical PhIP, which is produced during the digestion of heated and grilled meat. At the same time, the Western diet lacks protective vitamins and other micronutrients such as antioxidants that support DNA repair. Sugary soft drinks promote inflammation, which promotes tumor processes. Dyes, preservatives and other additives are suspected of causing genetic damage.
Lack of exercise
The younger generations sit – in the office, in front of screens, in their free time. Lack of exercise promotes obesity, insulin resistance and chronic inflammation – classic risk factors for cancer. A meta-analysis with four million participants revealed: Just two hours of additional sitting per day increases the risk of colon cancer by eight percent and of uterine cancer by ten.
Pesticides
Many approved active ingredients have not been adequately tested for long-term effects. Residues in fruits, vegetables or grains could cause oxidative stress and DNA damage. Children and pregnant women, or their unborn children, are considered particularly sensitive because their immune systems and detoxification mechanisms are still developing.
Hormones
Hormone-like substances enter the body through meat, dairy products or medications. They can disrupt the endocrine system and stimulate tumor growth. Estrogens and chemical substances such as bisphenol A, which are found in plastics, are particularly suspected.
Antibiotics
Their frequent use changes the microbiome – the bacterial community in the intestine that plays a key role in immune defense. A disturbed intestinal flora can promote inflammation and weaken the cancer defense. Its use in children is particularly problematic, especially in the case of unnecessary infections.
Colibactin
The poison molecule colibactin is produced by certain Escherichia coli bacteria in the intestine and is increasingly suspected of being a contributor to early colon cancer. Around a fifth to a third of people carry such bacterial strains – usually without becoming ill. Researchers suspect that diet, medications or other environmental factors stimulate toxin production and thus promote mutations in the genetic material. What is striking is that colibactin-typical mutation patterns are found much more frequently in industrialized countries than in rural regions of Africa or Asia.
Micro- and nanoplastics
Tiny plastic particles enter the body through water, food and air. They are deposited in the tissue, can trigger inflammation and act as a carrier of other harmful substances. Many plastics contain hormone-active additives that could influence cancer processes – but little is known about the biological consequences.
Early childhood influence
Early life conditions could also play a role. In the 1990s, cesarean births and appendix and tonsil removals increased. These interventions alter the microbiome and could influence the development of the immune system – possibly with long-term consequences.
Psychological stress
Mental health is also improving increasingly becoming the focus of cancer research. Studies show that depression, chronic stress, burnout and sleep disorders have increased significantly in the Millennials and Gen Z generations – and these factors could weaken the immune system’s defense against cancer cells. Constant stress also changes the hormonal balance and inflammatory processes, which can increase the risk of cancer.
The researchers led by the geneticist Bardelli emphasize that all of these factors do not work in isolation, but are part of a dense network of interactions. Nutrition, environment, medications, early interventions – everything is intertwined, many things reinforce each other. It is hardly possible to name a single “main culprit”.
Oncologist Sacha Rothschild also urges caution:
“Many of the suspected causes have not yet been sufficiently scientifically proven. We often don’t know whether there is real causality or just correlation.”
In order to gain clarity, large, long-term population studies are needed.
“But one thing is clear: we can influence lifestyle habits such as diet, exercise, consumer behavior and precautions. It makes social sense and is sustainable to maintain high standards, especially in these areas.”
That’s why he’s worried about the development of smoking: “The number of smokers has been decreasing for a long time, but among the youngest people it’s increasing slightly again due to vaping – we urgently need to take countermeasures.” (aargauerzeitung.ch)