Breast cancer can form ‘sleeper cells’ after drug treatment

Breast cancer medicines may force some cancer cells into ‘sleeper mode’, allowing them to potentially come back to life years after initial treatment.


Scientists at the Imperial College London has recently found that breast cancer medicines may put some cancer cells in sleeper mode and allow them to come back to life years later.

Scientists mainly studied a group of breast cancer drugs called hormone treatments. For quite a while researchers have discussed whether hormone treatments – which are an extremely effective treatment and spare a large number of lives – work by executing breast cancer cells or whether the medications flip them into a dormant ‘sleeper’ state.

The study paves the way towards discovering methods for keeping the cancer cells dormant for more or even possibly finding a method for arousing the cells so they would then be able to be killed by the treatment.

Dr. Luca Magnani, the lead author of the study from Imperial’s Department of Surgery and Cancer, said, “Our findings suggest the drugs may kill some cells and switch others into this sleeper state. If we can unlock the secrets of these dormant cells, we may be able to find a way of preventing cancer coming back, either by holding the cells in permanent sleep mode, or be waking them up and killing them.”

Scientists studied around 50,000 human breast cancer single cells in the lab and found that treating them with hormone treatment exposed a small proportion of them as being in a dormant state.

They noted, “the ‘sleeper cells’ may also provide clues as to why some breast cancer cells become resistant to treatment, causing a patient’s drugs to stop working, and their cancer to return.”

In a past study, scientists explored why breast cancer cells become resistant to hormone treatment. They found that the cells make their own ‘fuel,’ allowing them to avoid being ‘starved’ by cancer treatment.

Dr. Iros Barozzi, the co-author of the study, said, “This new research provides another piece in the puzzle. These sleeper cells seem to be an intermediate stage to the cells becoming resistant to the cancer drugs. The findings also suggest the drugs trigger the cancer cells to enter this sleeper state.”

Dr. Sung Pil Hong, the study co-author from Imperial, said, “The research also revealed cells in this dormant sleeper state were more likely to spread around the body. Our experiments suggest these sleeper cells are more likely to travel around the body. They could then ‘awaken’ once in other organs of the body, and cause secondary cancers. However, we still don’t know how these cells switch themselves into sleep mode – and what would cause them to wake up. These are questions that need to be addressed with further research.”

“Hormone therapies remain one of the most effective treatments against breast cancer, and that further patient research will explore whether taking hormone therapies for longer after initial cancer treatment could prevent cancer cells from waking from their sleeping state.”

Dr. Rachel Shaw from Cancer Research UK, said: “Although treatments for breast cancer are usually successful, cancer returns for some women, often bringing with it a poorer prognosis. Figuring out why breast cancer sometimes comes back is essential to help us develop better treatments and prevent this from happening. This study highlights key route researchers can now explore to tackle ‘sleeping’ cancer cells that can wake up years after treatment, which could potentially save the lives of many more women with the disease.”


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