Researchers have shown how a fatty acid found in palm oil can encourage the spread of cancer, in work that could pave the way for new treatments.
The study in mice showed that palmitic acid promoted metastases in mouth and skin cancer. Going forward, this process can be targeted with medications or carefully designed meal plans, but the team behind the work warned against patients going on diets in the absence of clinical trials.
“There is something very special about palmitic acid that makes it an extremely potent promoter for metastases,” said Professor Salvador Aznar-Benitah, of the Department of Biomedical Research (IRB), Barcelona. “I think it’s too early to determine what type of diet can be ingested by patients with metastatic cancer who would slow down the metastatic process.”
The study adds new evidence that diet can be used to improve existing cancer treatments because certain nutrients are disproportionately dependent on tumor cells or are needed at critical stages such as metastases.
The study was based on previous work by the same team, which shows that within a tumor, only a small subset of cells have the capacity to spread by traveling out of the tumor, reaching other organs and colonizing them. These specialized cancer cells appeared to be particularly dependent on fatty acids, and recent work has narrowed this to palmitic acid, which is found in palm oil – but also in a wide variety of foods such as butter and olive oil.
The study, published in Nature, found that when palmitic acid was supplemented with the mouse’s diet, cancer of the mouth and skin was more likely to spread. Other fatty acids called oleic acid and linoleic acid – omega-9 and omega-6 fats found in foods like olive oil and flaxseed – did not show the same effect. None of the fatty acids tested increased the risk of developing cancer in the first place.
The study suggested that exposure to palmitic acid caused changes in the function of genes in cancer cells, which allowed them to label fatty acids and consume them more efficiently. The presence of palmitic acid also appeared to send cancer cells into a “regenerative state” that allows them to form signal networks beyond the tumor, which is known to be a crucial step toward proliferation.
Metastatic cancer remains the leading cause of death in cancer patients, and the vast majority of people with metastatic cancer can only be treated but not cured.
By understanding what cancer cells need to take this leap, the researchers also identified ways to block the process and are planning a clinical trial with proteins that disrupt the tumor response to palmitic acid.
“It’s a much more realistic approach in terms of a real therapy that does not depend on whether a patient likes Nutella or pizza,” Aznar-Benitah said. “Playing with diets is so complicated.”
Prof Greg Hannon, Director of the Cancer Research UK Cambridge Institute, said: “This is a rigorous and comprehensive study that suggests that exposure to a significant component of palm oil permanently alters the behavior of cancer cells, making them more likely to develop from local to potentially fatal metastatic disease. Given the prevalence of palm oil as an ingredient in processed foods, this study provides a strong motivation for further study of how dietary choices affect the risk of tumor progression. “
Helen Rippon, CEO of Worldwide Cancer Research, said: “This discovery is a major breakthrough in our understanding of how diet and cancer are linked, and perhaps more importantly, how we can use this knowledge to launch new cures for cancer. Metastases are estimated to be responsible for 90% of all cancer deaths – that’s about 9 million deaths a year globally. Learning more about what causes cancer to spread and – what’s important – how to stop it is the way forward to reduce these numbers. ”