Researchers have warned that obesity may increase the risk of developing multiple types of cancer more than previously thought, stressing that weight loss can be an effective way to prevent these diseases.
A recent German study, published in JAMA Oncology, suggests that the link between obesity and cancer may have been significantly underestimated. The study used data from the UK, Germany, and Sweden to assess the long-term impact of excess weight on cancer risk.
In the UK, researchers analyzed data from 458,660 people from the UK Biobank and found that obesity was associated with 7.2% of gastrointestinal cancers diagnosed within four years of weight measurement, and the figure rose to 17.7% after more than four years, suggesting that weight loss due to illness before diagnosis may underestimate the relationship between obesity and cancer.
In Germany, a study of more than 10,000 people showed that continued weight gain over years is associated with a 55% increased risk of bowel cancer compared to relying on body mass index alone.
In Sweden, data from more than 339,000 people showed that men with larger waist circumferences faced a 25% higher risk of developing obesity-related cancers, compared to 19% when relying on body mass index alone, suggesting that abdominal fat may be a better indicator of risk than overall weight.
The results also indicated that the risk of developing cancer begins to increase even at body mass index (BMI) levels below 25, meaning that people currently classified as "overweight" may be at risk without realizing it. (BMI is a number used to assess whether a person's weight is appropriate for their height. It is calculated by dividing a person's weight in kilograms by the square of their height in meters.)
The researchers proposed a framework called "PLUS" to improve risk measurement, taking into account pre-diagnosis weight loss, using lifetime weight, as well as waist circumference, and suggesting that obesity prevention may be more effective in reducing cancer than previously thought.
The researchers called for the systematic integration of obesity control strategies into public health systems, noting that the study's findings are largely observational and do not definitively prove causation.
