A high-fat diet may contribute to the spread of breast cancer, researchers at the Spanish National Cancer Research Center (CNIO) have found. Their study, published in Nature Communications, sheds new light on how obesity fosters conditions that allow cancer cells to metastasize, particularly to the lungs.
How Obesity Affects Cancer Spread
Obesity has long been associated with an increased risk of breast cancer and metastasis, though the exact mechanisms remained unclear. Led by Héctor Peinado, head of CNIO’s Microenvironment and Metastasis Group, the new research was conducted using animal models of triple-negative breast cancer, a particularly aggressive form of the disease.
The findings suggest that excessive fat intake triggers biological changes that help cancer cells spread. The study identified two key factors contributing to metastasis: enhanced blood clotting and increased production of fibronectin, a protein that supports tumor cell attachment in the lungs.
The Role of Platelets in Protecting Tumor Cells
One of the study’s key discoveries is that obese mice, fed a high-fat diet, exhibited increased platelet activation and blood clotting. Platelets are blood cells essential for clotting, but they also play a role in shielding cancer cells.
Marta Hergueta, a CNIO researcher and the study’s first author, observed that tumor cells in obese mice were surrounded by more platelets than those in animals with a normal diet. Peinado suggests that these platelets form an “armor” around cancer cells, making them harder for the immune system to detect and destroy.
A Fertile Ground for Metastasis
Beyond platelet protection, the study found that a high-fat diet stimulates fibronectin production in lung tissue, creating a more favorable environment for cancer cells to establish themselves.
“Fibronectin not only helps build lung tissue but also facilitates interactions between tumor cells and platelets,” Peinado explained. These interactions may encourage the formation of premetastatic niches—areas in the body where cancer cells can settle and grow.
Implications for Human Patients
To determine whether these findings translate to human cases, CNIO researchers analyzed blood samples from triple-negative breast cancer patients. Although the study did not confirm a direct link between obesity and metastasis in humans, it found that patients with higher blood clotting tendencies—indicated by shorter prothrombin times—faced a higher risk of relapse within five years.
According to Peinado, these findings could help doctors identify additional risk factors in breast cancer patients, potentially leading to improved clinical management strategies.
Can Diet Influence Metastasis Risk?
The study also explored potential clinical applications by modifying the diets of obese mice. When the high-fat diet was withdrawn and the mice lost weight, their platelet and coagulation behavior returned to normal, leading to a reduction in metastases.
Peinado believes these results align with other clinical studies that suggest dietary interventions could enhance the effectiveness of cancer treatments. “Dietary changes alone won’t act as a standalone treatment, but they could complement existing therapies by reducing metastasis risk,” he said.
Funding and Collaboration
The study was supported by the British NGO Worldwide Cancer Research, as well as funding from Spain’s Ministry of Science and Innovation, the State Research Agency, the Carlos III Health Institute, and European ERDF funds. Additional support came from private grants from the la Caixa Foundation and the Spanish Association Against Cancer (AECC).
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