Obesity is a significant driver behind the rising incidence of cancer among adults under the age of 50, according to a major new study. While not the sole cause, researchers believe excess weight contributes through mechanisms such as increased insulin levels and inflammation.
Study Findings
The study, published in BMJ Oncology, analyzed national cancer registry data from England between 2001 and 2019. It found that rates of several cancers have increased in younger adults over the past two decades, while many traditional risk factors like smoking, alcohol consumption, and poor diet have remained stable or declined. In contrast, overweight and obesity rates have steadily risen since 1995, suggesting a key role in the uptick.
However, increases in body mass index (BMI) alone do not account for the entire rise. The researchers estimate that around 20% of the increase in bowel cancer among younger adults is attributable to rising BMI, with other factors still unexplained.
Cancers on the Rise
Eleven cancers were identified as increasing in the 20–49 age group, all linked to lifestyle and behavioral risk factors: thyroid, multiple myeloma, liver, kidney, gallbladder, colorectal, pancreatic, endometrial, oral, breast, and ovarian cancers. All except oral cancer are known to be associated with excess weight.
Bowel and ovarian cancers are unique in that they are rising only in younger adults, while the other nine are also increasing in older populations.
Expert Commentary
Professor Montse Garcia-Closas from the Institute of Cancer Research (ICR) stated that around 15% of bowel cancer in younger people could be due to overweight or obesity, with combined known risk factors accounting for 40–50% of cases. She emphasized that much of the increase remains unexplained, likely due to multiple factors acting together.
Professor Marc Gunter from Imperial College London noted that obesity is a risk factor for about 19 different cancers. He explained that higher insulin levels in people with obesity may promote cancer growth, particularly in early-onset colorectal cancer.
Public Health Implications
The researchers call for large-scale, long-term studies to identify all contributing factors. However, they stress that the evidence is strong enough to prioritize obesity reduction, especially among children and young people, as a public health measure.
Professor Amy Berrington from ICR reminded that cancer in young people remains rare, but the trend warrants action. Michelle Mitchell, CEO of Cancer Research UK, highlighted the need for stronger policies on junk food advertising and healthy food access, alongside continued efforts to reduce smoking.
