A new study led by epidemiologist Hermann Brenner of the German Cancer Research Center (DKFZ) suggests that up to 11.5% of cancer cases may be attributable to excess body weight, significantly higher than the 2% to 8% previously estimated by researchers. The study, which drew on health data from 458,543 participants in the UK Biobank followed for an average of 12 years, identified 50,000 new cancer cases during the observation period and examined the relationship between body weight and 13 types of cancer, including colon, breast, and liver cancer.
Study suggests excess body weight linked to more cancer cases than previously estimated
A new study led by epidemiologist Hermann Brenner of the German Cancer Research Center (DKFZ) suggests that up to 11.5% of cancer cases may be attributable to excess body weight, significantly higher than the 2% to 8% previously estimated by researchers. The study, which drew on health data from 458,543 participants in the UK Biobank followed for an average of 12 years, identified 50,000 new cancer cases during the observation period and examined the relationship between body weight and 13 types of cancer, including colon, breast, and liver cancer.
Previous research on the link between obesity and cancer relied primarily on body mass index (BMI), a measure calculated from height and weight. The DKFZ team's updated methodology also incorporated waist circumference and waist-to-hip ratio, on the basis that BMI does not distinguish between fat and muscle mass and does not indicate how fat is distributed across the body.
The researchers focused particular attention on abdominal fat, which, according to the study, functions differently from fat stored elsewhere in the body. Rather than acting as a passive caloric store, abdominal fat cells release signaling molecules known as adipokines into the bloodstream. These molecules influence metabolic processes including cell growth and division, as well as the inhibition of programmed cell death — mechanisms described in the study as potentially contributing to tumor development and growth.
The DKFZ team also sought to address a methodological problem identified in earlier studies: cancer can cause weight loss before diagnosis, meaning participants may already have lost weight by the time they enrolled in previous studies, obscuring the statistical association between obesity and cancer. To account for this, the researchers excluded cancer cases that occurred within the first seven years of the observation period, which they reported made the statistical link between excess weight and cancer more apparent.
The study found that overweight women developed cancer at a higher proportion than overweight men. The researchers noted that certain cancers affecting women — including breast, uterine, and ovarian cancers — are hormone-dependent. Excess abdominal fat can contribute to elevated estrogen levels, which in turn may stimulate the growth of cancers such as breast cancer.
Michael Leitzmann, an epidemiologist at the University of Regensburg's Institute of Epidemiology and Prevention who was not involved in the study, stated that the DKFZ researchers had not only updated existing risk estimates but had also raised the question of whether the link between excess weight and cancer had been systematically underestimated. Leitzmann advised caution in interpreting the finding that women are at higher proportional risk, noting that further studies using a similar design would be needed to determine whether the results could be replicated.
- The study's findings have not been summarized with full statistical breakdowns for each of the 13 cancer types examined.
- The DKFZ researchers themselves are not directly quoted in the article; their positions are described only through the study's findings and Leitzmann's characterization.
- No information is provided on whether the study has been peer-reviewed or in which journal it was published.
- The mechanism by which the seven-year exclusion threshold was determined is not explained.
- No data are provided on the sex breakdown of the 458,543 UK Biobank participants or the 50,000 cancer cases identified.
Read the original at Deutsche Welle