After analyzing data from more than 700,000 people, an international team of scientists discovered that the risk of developing certain types of cancer depends not so much on the total amount of body fat, but rather on where that fat is located.

Which Fat Deposits Were Studied

Researchers led by Emma Hazelwood from the University of Bristol examined five types of fat deposits—meaning fat reserves concentrated in specific anatomical areas:

• subcutaneous abdominal fat (under the skin of the abdomen),
• visceral fat (around the internal organs in the abdominal cavity),
• gluteofemoral fat (hips and buttocks),
• liver fat,
• pancreatic fat.

How the Study Was Conducted

The analysis used the Mendelian randomization method, which allows researchers to determine whether genetically predicted levels of a particular risk factor are linked to the likelihood of developing a disease. The study included data from hundreds of thousands of participants in the largest genetic studies, with the maximum sample size reaching 728,000 people.

Main Findings

The results, published in the Journal of the National Cancer Institute, showed:

• Excess abdominal fat increases the risk of endometrial cancer (cancer of the uterine lining in women), liver cancer, and esophageal adenocarcinoma, but lowers the likelihood of some aggressive forms of breast cancer.
• Visceral fat increases the risk of liver cancer by more than four times.
• Fat in the pancreas raises the risk of endometrioid ovarian cancer, but reduces the risk of proximal colon cancer.
• Fat in the hips and buttocks, on the other hand, has a protective effect, lowering the risk of breast cancer and meningioma.

Mechanisms of Influence

The researchers also explored the biological mechanisms behind these associations:

• Excess subcutaneous abdominal fat lowers the concentration of sex hormone-binding globulin and increases the level of available testosterone, which partly explains the risk of developing endometrial cancer.
• About 42% of the increased risk of esophageal adenocarcinoma associated with abdominal fat is explained by a decrease in the level of IGFBP-1 protein, which regulates the action of insulin-like growth factors.
• Roughly 27% of the protective effect of gluteofemoral fat is linked to higher levels of adiponectin—a hormone that regulates metabolism and has anti-inflammatory properties.

Practical Recommendations

According to the scientists, up to a third of liver cancer cases in the population may be associated with an excess of so-called "dangerous" fat tissues—visceral fat and liver fat. At the same time, body mass index (BMI) does not always reflect the real situation: a person may have a normal weight but a high level of fat in the liver or around the abdominal organs.

The study authors note that clinical practice should gradually move away from simply assessing body weight toward more precise methods, such as MRI or biomarker analysis, which can determine exactly where fat is accumulating in the body.