Metastasis – or the spread – of cancer remains the main cause of death in cancer patients and the vast majority of people with metastatic cancer can only be treated, but not cured. Fatty acids are the building blocks of fat in our body and the food we eat. Metastasis is promoted by fatty acids in our diet, but it has been unclear how this works and whether all fatty acids contribute to metastasis.

Newly published findings, led by researchers at IRB Barcelona, Spain, reveal that one such fatty acid commonly found in palm oil, called palmitic acid, promotes metastasis in oral carcinomas and melanoma skin cancer in mice. Other fatty acids called oleic acid and linoleic acid – omega-9 and omega-6 fats found in foods such as olive oil and flaxseeds – did not show the same effect. Neither of the fatty acids tested increased the risk of developing cancer in the first place.

The research found that when palmitic acid was supplemented into the diet of mice, it not only contributed to metastasis, but also exerts long-term effects on the genome. Cancer cells that had only been exposed to palmitic acid in the diet for a short period of time remained highly metastatic even when the palmitic acid had been removed from the diet.

The researchers discovered that this “memory” is caused by epigenetic changes – changes to how our genes function. The epigenetic changes alter the function of metastatic cancer cells and allow them to form a neural network around the tumor to communicate with cells in their immediate environment and to spread more easily. By understanding the nature of this communication, the researchers uncovered a way to block it and are now in the process of planning a clinical trial to stop metastasis in different types of cancer.