Selenium: Could a common food supplement help prevent the spread of cancer?

The key to helping prevent the spread of cancer could be in your shopping basket.

Selenium, which is found mostly in Brazil nuts, seafood and cereals (and a popular ingredient in multivitamins), is crucial for our health. It supports thyroid function, boosts our immune system and can help protect our cells from damage. Some previous studies have even looked at how selenium supplements could be used to help prevent cancer.

But new research, funded by Cancer Research UK, shows that cancer cells are actually in great need of the mineral to keep them functioning as they try and spread through the body (metastasise). That means selenium deprivation could be the basis for a new type of triple negative breast cancer treatment.

Selenium starvation

Without selenium, cells are more likely to die through a process called ferroptosis. This is a type of ‘programmed cell death’: a self-destruct mechanism designed to go off when cells are in danger of causing damage or becoming cancerous.

But none of our body’s defences are perfect. This new research, published in EMBO Molecular Medicine shows that when triple negative breast cancer cells cluster together they are able to protect themselves from ferroptosis. They produce a type of fat molecule containing oleic acid (commonly found in olive oil) which is triggered by a lack of selenium, so they can continue to grow and spread.

But if the cancer cells are away from these clusters, such as when they are moving to other parts of the body, they are more vulnerable to ferroptosis from a lack of selenium.

“We need selenium to survive, so removing it from our diet is not an option,” said Dr Saverio Tardito, who led the research.

Dr Saverio Tardito smiling in front of a board detailing some of the metabolic pathways this research looks at. — Dr Saverio Tardito. Behind him is a board detailing some of the metabolic pathways this research looks at.

“However, if we can find a treatment that interferes with the uptake of this mineral by triple negative breast cancer cells, we could potentially prevent this cancer spreading to other parts of the body.”

Tardito also explained why this could be so important.

“It is not usually breast cancer itself that proves fatal as it can often be tackled successfully with treatment or surgery,” he said. “It is when the cancer spreads that it proves harder to control.”

Tardito’s team found that interfering with the metabolism of selenium in sparse cancer cells was an effective way of killing them – particularly when they were travelling through the blood to metastasise. The team’s research could be a way to turn triple negative breast cancer from a potentially fatal disease into a manageable one.

Transforming fatal into manageable

Around 56,800 people in the UK are diagnosed with breast cancer each year, with around 15% of those being diagnosed with triple negative breast cancer. But there are fewer treatments for triple negative breast cancer compared to other forms of breast cancer because of the lack of receptors.

Triple negative breast cancers don’t have receptors for the hormones oestrogen and progesterone, or a protein called Human Epidermal Growth Factor Receptor 2 (HER2). That means it can be harder to treat than other types of breast cancer, as doctors can’t use hormone therapies or targeted cancer drugs.

“Outcomes for patients with triple negative breast cancer can be worse than for other types of cancer,” explained Dr Sam Godfrey, our director of research. “Research like this could be the key to preventing this type of cancer spreading, and that would have a transformative effect on how this disease is treated.”