The numbers are alarming. In some types of cancer, the number of cases has doubled over the past 20 years. However, it is not entirely clear whether the number of cases has actually doubled, or whether more cases are being detected at earlier stages due to improved awareness, development of diagnostic methods, and availability of treatment options in hospitals.
Take colon cancer, for example: this type of cancer was diagnosed in England in 2001 in one out of every 26,000 people under the age of fifty. In 2023, the infection rate was one case out of every 12,000 people, double what it was at the turn of the millennium. The figures were released by the World Cancer Research Fund (WCRF), an international network of organizations and charities that analyzes cancer registry data from England, the United States and the Netherlands.
Although the numbers have doubled, they are still low overall, said Amy Berrington de Gonzalez, professor of clinical epidemiology at the Institute of Cancer Research in London. "Cancer is still rare among young people," she told DW. “Tripling a small number is still a small number,” she continued. Yet she - like other scientists too - wants to know why the numbers are rising. Because this is ultimately about global development. A good example of this is Latin America.
In a study from 2025, health record data from 50 countries and regions were analyzed for the period extending to 2017. In 27 of these regions, the number of colon cancer cases among young people increased. This rise has been observed in Latin America in countries such as Chile, Argentina, Ecuador, Costa Rica and Puerto Rico. One of the highest rates of increase recorded in Chile is about 4 percent per year.
Mark Gunter, professor of cancer epidemiology at Imperial College London, believes Latin America will follow wealthier countries in its development, adopting dietary habits that are increasingly geared towards a Western lifestyle and sedentary daily life. “I think this is already happening,” Gunter says.
His colleague, Professor Berrington de Gonzalez, stresses: “We need better systems for recording cancer cases. Especially in countries like Brazil and Mexico, where obesity rates have also risen.”
In another study from 2025 that used data from 42 countries, Berrington de Gonzalez compared data from 2003 to 2017 for two age groups: young people aged 20 to 49, and people over 50. In most countries, the incidence of six types of cancer (thyroid, breast, colon, kidney, uterine, and leukemia) has increased among young people. With the exception of colon cancer, the incidence of these cancers has also increased in the group of people over 50 years of age.
In fact, the numbers for colon cancer were exceptional. In about a third of the countries included in the study, infection rates among young people were higher than among the elderly. Regarding this, Berrington de Gonzalez explained, “This type of cancer seems to be the only one whose rates are high among young people, while they are low among the elderly.”
This affects scientific research. If the number of cancer cases increases across all age groups, the causes are likely to be widespread. If studies are limited to young people, there is a big risk of pursuing complex explanations without being able to verify them with sufficient data, Berrington de Gonzalez says.
A US study of pancreatic cancer in adults aged 15 to 39 years showed that the rise in incidence was almost entirely due to early-stage tumors. While the death rate remained unchanged. The study's authors conclude that this is not related to an increase in the number of cancer cases, but rather to improved early detection, which can be explained by increased awareness among the population and a higher level of willingness to conduct preventive examinations.
As for colon cancer, the data shows a different picture: some American studies show that the numbers also rise in advanced stages. This suggests that the number of cases of the disease is increasing, not just the number of cases being diagnosed.
According to the International Agency for Research on Cancer (IARC) of the World Health Organization, obesity is a proven cause of at least 13 types of cancer.
An analysis of existing studies conducted in 2021 showed that the probability of developing colon cancer doubles before the age of fifty among young people who suffer from obesity. Obesity has spread at its fastest rates among young people in particular. Since the 1990s, the number of adults suffering from obesity has doubled, while it has quadrupled among young adults, according to data from the World Health Organization.
Diet has a big impact: processed meats are carcinogenic, alcohol is also a risk factor, while dietary fiber (vegetables, whole grains and legumes) reduces the risk of cancer.
It is assumed, according to some experts, that ultra-processed food and microplastics may also cause cancer, but the evidence for this is not conclusive, says Professor Gunter. He warns that “there is a lot of media hype,” stressing the need for more research. Professor Berrington de Gonzalez agrees, saying: “Dietary habits have changed, but we still do not know what role the changes may play.”
In this regard, Gunther says, we should not blame people for living in societies that depend on ready-made meals and office jobs. He adds that achieving sustainable change requires a different health policy. But Gunter also emphasizes that young people can reduce their risk of cancer by maintaining a healthy weight, getting more physical activity, eating more fiber, and reducing consumption of processed meat.
“Walking, getting more physical activity, eating more fruits and vegetables – all of these things may be uncommon now, but they are very important,” says Gunter. Berrington de Gonzalez has a reassuring message for all 30-year-olds reading this article: “Cancer cases among young people are still relatively rare.”
