A new study reveals that 11 cancers are rising in the under-50s, with obesity contributing to the alarming trend

A groundbreaking new study has found that 11 types of cancer are on the rise in people aged 20 to 49, with obesity emerging as a significant driver of this worrying trend. The cancers in question include thyroid, multiple myeloma, liver, kidney, gallbladder, colorectal, pancreatic, endometrial, oral, breast, and ovarian cancers. While obesity has been identified as a key factor in most of these cases, experts caution that further research is needed to fully understand the causes behind the increasing incidence of cancer in younger adults.

Researchers at the Institute of Cancer Research, London (ICR) and Imperial College London conducted the study, which highlights the connection between excess weight and the growing number of cancer cases in individuals under 50. Specifically, obesity is thought to increase the risk of cancer due to elevated insulin levels and chronic inflammation. While the study found that obesity plays a significant role, other factors may also be contributing to the rise in cancer rates, and these remain to be fully explored.

The study, published in the journal BMJ Oncology, noted that while the overall number of cancer diagnoses in the under-50 age group is still relatively low, the increase in cases is concerning. In 2023, approximately 31,000 cancer cases were diagnosed in the UK among people aged 20 to 49, compared to 244,000 cases in those aged 50 to 79. This suggests a growing disparity in cancer incidence between younger and older adults, especially as traditional risk factors such as smoking, alcohol consumption, and diet have remained relatively stable or declined.

Bowel and ovarian cancers are particularly alarming, with rates in younger adults rising more sharply than in older populations. Researchers found that for women, the rates of BMI-linked bowel cancer increased faster than those not associated with BMI, particularly in younger age groups. Despite this, BMI-linked bowel cancer remains less common in younger adults compared to those with no link to BMI, indicating that other unknown factors could be at play.

Experts have also suggested that lifestyle factors such as the consumption of ultra-processed foods, antibiotic use, and air pollution could contribute to the increasing cancer rates. However, many of these factors have shown either stable or declining trends in the UK, further complicating the search for clear answers.

One key takeaway from the study is that while BMI is a strong clue, it does not account for all of the rising cancer rates in younger adults. Professor Montse García-Closas from ICR stressed that while more research is needed, the evidence linking obesity to cancer is clear enough that public health action should be taken now.

Professor Amy Berrington from ICR noted that, despite the rise in cancer rates, it remains a relatively rare disease in younger people. However, the trend cannot be ignored, especially as obesity has been linked to around 19 different types of cancer, including colorectal cancer. Elevated insulin levels and inflammation, both of which are common in individuals with obesity, are thought to be contributing factors to early-onset cancers.

Michelle Mitchell, Chief Executive of Cancer Research UK, acknowledged the complexities of the issue, but emphasised the importance of addressing obesity to reduce the burden of cancer. She also pointed out that improvements in early detection are likely contributing to the rise in diagnosed cases, meaning more people are being diagnosed at a younger age.

The researchers call for large-scale, long-term studies to better understand the biological and environmental factors driving this increase. However, they agree that tackling obesity, particularly in children and young adults, must become a public health priority. Initiatives to reduce obesity rates through better access to healthy food, exercise, and public health policies are essential steps in addressing this growing issue.