Obesity Linked to More Cancer Cases Than Previously Thought, Study Finds; Second Leading Cause After Smoking

A groundbreaking study has revealed that obesity is responsible for more cancer cases than previously estimated, raising urgent concerns about public health strategies. Researchers from Germany analyzed data across the UK, Germany, and Sweden, finding that obesity's link to cancer may have been "strongly underestimated." In Britain alone, over 18,000 preventable cancer cases are now linked to obesity, making it the second-largest cause of the disease after smoking. "This is a wake-up call," said Dr. Lena Müller, lead author of the study. "We're seeing a far greater connection between obesity and cancer than we thought."

The research, published in *JAMA Oncology*, examined data from 458,660 UK participants in the UK Biobank. It found that obesity was linked to 7.2% of gastrointestinal cancers diagnosed within four years of weight measurement. However, when considering cancers diagnosed later, the link jumped to 17.7%. This discrepancy suggests that people with undiagnosed cancer often lose weight before diagnosis, skewing earlier estimates. "We're missing a significant portion of the risk because current models don't account for this," explained Müller.

In Germany, the study found that being overweight for extended periods increased bowel cancer risk by 55% compared to BMI alone. Meanwhile, in Sweden, men with larger waist sizes had a 25% higher risk of obesity-related cancers than those with higher BMIs but smaller waists. "Waist size may be a better indicator of risk for men than overall weight," noted the study's co-author, Dr. Eriksson. The findings also showed that cancer risk rises even at BMIs below 25, meaning current overweight thresholds may overlook at-risk individuals.

The researchers proposed a new framework called PLUS to improve risk assessment. It includes factors like lifetime weight history, pre-diagnosis weight loss, and waist size. "PLUS reveals that obesity prevention could be one of the most powerful cancer strategies," said Müller. The study's authors urged governments to integrate obesity prevention into public health systems, emphasizing the urgency of addressing the obesity epidemic.

Public health experts have echoed these calls, noting that obesity is already linked to diabetes, heart disease, and other conditions. "This study adds cancer to the list of reasons to act now," said Dr. Sarah Lin, a cancer prevention specialist. "Losing weight isn't just about appearance—it's a life-saving measure." However, the researchers stressed that their findings are observational, and causation hasn't been proven. Still, the evidence is compelling enough to demand action. "The time to rethink how we measure and address obesity is now," concluded Müller.