Overweight and obesity: a key factor in the rise of cancers among under-50s in England

A recent study conducted by Imperial College London and the Institute of Cancer Research[1]-[2] This study highlights the major role of overweight and obesity in the increase of cancers among adults under 50 in England. Between 2001 and 2019, the incidence of 11 types of cancer increased in this age group, the vast majority of which are associated with a high body mass index (BMI). Overweight is thought to be implicated in 10 of these 11 cancers, including colorectal, pancreatic, ovarian, kidney, and endometrial cancers. Researchers estimate, for example, that a significant proportion of certain cancers could be prevented by maintaining a healthy weight, with proportions reaching approximately 20% for colorectal cancer and up to 35% for endometrial cancer.

A documented increase among young adults

The analysis highlights a significant increase in cancers among 20- to 49-year-olds over nearly two decades. Of the cancer types studied, 11 showed an increase in this age group, with notable rises for colorectal, kidney, pancreatic, ovarian, and endometrial cancers. In 2023, approximately 31,000 cases were diagnosed in young adults in England, representing nearly one in 1,000 people. Among the most common cancers were breast cancer (approximately 8,500 cases), colorectal cancer (3,000 cases), and melanoma (2,800 cases).

This trend is all the more remarkable given that it occurs within a context of declining smoking rates, particularly among young people. Historically, tobacco was the leading preventable risk factor for cancer, and its decline contributed to the decrease or stabilization of several cancers in older generations, notably lung and upper aerodigestive tract cancers. The increase observed among young adults thus suggests a shift in the risk profile, with a lesser relative contribution from tobacco but other emerging determinants.

Certain trends are particularly pronounced among younger generations. Colorectal cancer, in particular, is increasing rapidly in this age group, contrasting with the trends observed in older populations. In the latter group, prevention policies and screening programs have led to earlier diagnoses and improved prognoses. Conversely, young adults, less involved in these initiatives, are often diagnosed at a more advanced stage of the disease.

Being overweight, a growing factor that can be compounded by other risk factors

The research identifies overweight and obesity as the main risk factor that increased over the study period. Unlike smoking and alcohol consumption, which generally decreased or stabilized, excess weight is the only determinant that showed a continuous increase among young adults.

On a biological level, excess weight acts via inflammatory, hormonal and metabolic mechanisms that promote tumor development, particularly for certain digestive and hormone-dependent cancers.

The rise in overweight and obesity is emerging as a significantly increasing risk factor, with direct repercussions on the incidence of several cancers. Data shows, in particular, that in young women, colorectal cancers associated with a high body mass index are progressing more rapidly than those not linked to it, increasing from 0.9 to 1.6 cases per 100,000 people. More broadly, approximately 15 to 20% of colorectal cancers in young people could be attributable to being overweight. As Montse Garcia-Closas pointed out, these cancers are part of a cumulative risk factor: between 40% and 50% of cases are thought to be linked to combined factors such as obesity, sedentary lifestyle, alcohol consumption, and smoking.

Adapting prevention policies to a new risk landscape

The observed trends highlight the need to adapt prevention policies to these changes in the risk profile. The rise in cancers among those under 50 appears to be multifactorial and still only partially explained. While being overweight is a major contributing factor, it is not sufficient on its own to account for all the observed trends. Advances in screening and diagnosis could also contribute to identifying more cancers at an earlier age.

In this context, the fight against smoking remains a central pillar of prevention policies, as it remains one of the leading causes of cancer, including in adults under 50. The recent adoption of the Tobacco and Vapes Bill in the United Kingdom, which includes ambitious measures to limit access to and the appeal of tobacco and nicotine products, is part of a strategy to strengthen the protection of public health, particularly for younger generations, and to reduce their exposure to highly addictive and carcinogenic products.

At the same time, prevention strategies must more systematically integrate the determinants of overweight. This requires the adoption of structural policies aimed at regulating the advertising and promotion of unhealthy food products, improving access to a balanced diet, and fostering environments conducive to healthier lifestyles. These measures largely echo the proven prevention policies adopted to combat smoking.

©Generation Without Tobacco

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[1] Jane Kirby, Cancer in the under-50s: Obesity is an important driver, researchers warn, The Independent, published on April 29, 2026, accessed the same day

[2] Tobi Thomas, Obesity a key factor for rising cancer rates in young people in England, study finds, The Guardian, published on April 29, 2026, accessed the same day

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