Chinese scientists, in research published by the Proceedings of the National Academy of Sciences, suggest that consuming excessive fatty foods may exacerbate breast cancer.

The team, led by doctors and scientists from Sun Yat-Sen University in Guangzhou, warned that obesity "might contribute to accelerating tumor progression or diminish the effectiveness of chemotherapy, ultimately leading to a poorer prognosis."

A high-fat diet is a "high-risk factor for the malignant progression of cancers through the disruption of the intestinal microbiota," according to the researchers, who said that "obesity-related gut microbiota was associated with poor prognosis and advanced clinicopathological status in female patients with breast cancer."

The findings were derived from what the team described as "analysis of clinical data, genetic sequencing of gut microbiota and mouse models."

The tests and analysis showed that gut microbiota linked to a high-fat diet caused the body to produce too much leucine, an amino acid, a process that they said promoted "accelerated progression and worsening outcomes for breast cancer and melanoma."

At the same time, however, the tests pointed to a "gut–bone marrow–tumor axis" that could in turn prove "a broad avenue for anticancer therapeutic strategies" based on targeting the gut.

Other research has pointed to excess weight as a cause of cancer, according to the University of Texas. "After choosing not to smoke, keeping a healthy weight is the most important way you can reduce your risk of cancer," the Irish Cancer Society warns on its website.

The number of people worldwide classed as obese doubled to almost 900 million between 1990 and 2022, according to country data gathered by the World Health Organization, which in turn estimates that around 2.5 billion of the world’s adults are overweight.