The increased risk of digestive system cancers was primarily attributable to genes that influence fat mass.

“This means that fat mass is a more important risk factor than body size and that high BMI is not necessarily a risk factor for many different cancer types, but mainly for cancers of the digestive system,” says Susanna Larsson.

Moreover, genetic predisposition to increased BMI was associated with an increased risk of endometrial, ovarian, and lung cancer, but with a decreased risk of breast and prostate cancer.

Higher risk with more cells

The study did not provide evidence about the mechanisms behind the associations, but it is generally thought that tall people have higher cancer risk because they have more cells in their body.

According to the researchers, the link between fat mass and digestive cancers may be driven by increased consumption of cancer-causing substances in fatty food, or increased levels of fatty tissue increasing inflammation in the digestive tract.

Links between obesity and gender-specific cancers are likely driven by the production of reproductive hormones in fatty tissue.

The study was done in collaboration with researchers at the University of Cambridge and the University of Bristol, UK. There was no specific funding for this study.

This news article is based on a press release from the University of Cambridge.