A new preclinical study from Weill Cornell Medicine reveals that linoleic acid, a type of omega-6 fatty acid commonly found in seed oils and animal products, can promote the growth of triple-negative breast cancer (TNBC)—one of the most difficult-to-treat forms of breast cancer.
The findings, published March 14 in Science, may lead to more personalized dietary guidelines and therapeutic targets for cancer patients.
Linoleic acid is widely present in soybean oil, safflower oil, pork, and eggs.
While it is considered an essential fatty acid important for health, its levels have skyrocketed in Western diets since the mid-20th century due to the rise of ultra-processed and fried foods.
Although past studies have explored whether this increase contributes to cancer, results have been inconsistent, and no biological mechanism had been clearly identified—until now.
Led by Dr. John Blenis, the research team discovered that linoleic acid fuels tumor growth in TNBC by activating a critical cellular pathway known as mTORC1, which regulates metabolism and cell growth.
This effect is made possible through the action of a protein called FABP5 (fatty acid-binding protein 5), which is found in high levels specifically in triple-negative breast tumors.
In laboratory and mouse models, the researchers found that linoleic acid binds to FABP5, triggering mTORC1 activationand tumor progression—but only in triple-negative tumors, not in hormone-sensitive subtypes.
Mice with TNBC fed a high-linoleic-acid diet showed increased FABP5 levels, more aggressive tumor growth, and more active mTORC1 signaling. Blood and tumor samples from newly diagnosed TNBC patients also showed elevated linoleic acid and FABP5, supporting the relevance of the findings to human disease.
“This discovery clarifies the biological link between certain dietary fats and cancer growth,” said Dr. Blenis. “Importantly, it also shows that not all cancers respond the same way. For triple-negative breast cancer, linoleic acid appears to be a driver.”
Triple-negative breast cancer accounts for roughly 10–15% of all breast cancers and is notoriously difficult to treat because it lacks the hormone receptors that other breast cancer treatments typically target. Currently, there are no approved targeted therapies for TNBC.
FABP5, the protein that enables linoleic acid to activate tumor growth, could now serve as a biomarker for identifying patients who may benefit from dietary modifications or drug interventions. “This could help guide personalized nutrition advice and future treatment strategies,” said first author Dr. Nikos Koundouros.
The study also suggests that this same omega-6-FABP5-mTORC1 signaling pathway may be active in other cancers, including certain forms of prostate cancer. Researchers are now exploring whether this mechanism contributes to other diseases linked to metabolism, such as obesity and diabetes.
While linoleic acid remains an essential nutrient and plays a positive role in many biological processes, the study highlights the importance of context—especially in patients with specific cancer subtypes like TNBC, where dietary fat may influence disease progression in a more direct way than previously understood.
In short, the findings do not call for the general elimination of linoleic acid or seed oils from the diet, but they do suggest that in certain individuals—particularly those with triple-negative breast cancer—dietary intake of linoleic acid may need to be carefully managed as part of a broader, personalized approach to cancer care.
If you care about breast cancer, please read studies about how eating patterns help ward off breast cancer, and soy and plant compounds may prevent breast cancer recurrence.
For more health information, please see recent studies about how your grocery list can help guard against caner, and a simple way to fight aging and cancer.
The research findings can be found in Science.
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