Metabolic disease, with or without obesity, raises the risk of certain cancers, according to researchers in a European collaboration run by Lund University. This large-scale study looked at health data from more than 20,000 patients. Results show that metabolically unhealthy people are at a higher risk of malignancies associated with obesity, regardless of their body weight.
“The study shows the importance of assessing different metabolic risk profiles in addition to obesity, in order to be able to identify the groups that can benefit most from interventions to reduce their risk of suffering from obesity-related cancers”, said Ming Sun, a PhD student and first author of the paper.
The study was published recently in the Journal of the National Cancer Institute. It included data from health surveys and national registries including nearly 800,000 individuals through the years 1972-2014 from Sweden, Norway, and Austria.
By weighing data on blood pressure, blood glucose, and blood fats (in the form of triglycerides), the team produced a score that determined whether subjects were considered metabolically healthy or unhealthy. Based on BMI (Body Mass Index), the participants were also divided into the categories of normal weight, overweight, or obese.
“Being metabolically unhealthy is often linked to obesity, but you also don’t have to be overweight to have a metabolically unhealthy status. Therefore, it is relevant to study how this status plays a role in the relationship between BMI and obesity-related cancer,” says Tanja Stocks, epidemiology researcher who led the study.
It is known that obesity is linked to more than ten different cancers, with some differences between men and women. Worldwide the rate of obesity has tripled since 1975, according to the World Health Organization. By 2016 almost 40% of adults over 18 were overweight and 13% were obese.
This study included 23,630 individuals from the Metabolic Syndrome and Cancer Project 2.0, which is a pooling of 6 cohorts from the three European countries.
The researchers found that a higher BMI increased the risk of cancer, but being metabolically unhealthy was also associated with an increased risk. The highest risk was found among individuals with metabolically unhealthy obesity, which was associated with cancer of the liver, kidney, and among women, also for endometrial cancer.
But the researchers also found that metabolic unhealth in itself represented an increased risk of obesity-related cancer – regardless of whether one was of normal weight, overweight, or obese.
How obesity causes cancer is not yet clear, but there is evidence that the key link is inflammation, and that activation of the kynurenine pathway affects feeding, metabolism, and carcinogenesis promotion. Notably, bariatric surgery cuts obese patients’ cancer risk by half.
