Dormant but still dangerous

Breast cancer medicines may force some cancer cells into “sleeper mode”, allowing them to potentially come back to life years after initial treatment, a researcher team led by Imperial College London, UK, suggests.

In an early-stage trial they studied around 50,000 human breast cancer single cells in the lab and found that treating them with a hormone treatment exposed a small proportion of them as being in a dormant state.

They scientists say these “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.

“For a long time, scientists have debated whether hormone therapies – which are a very effective treatment and save millions of lives – work by killing breast cancer cells or whether the drugs flip them into a dormant sleeper state,” says lead author Luca Magnani.

“This is an important question as hormone treatments are used on the majority of breast cancers.”

“Our findings suggest the drugs may actually 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.”

The study is published in the journal Nature Communications.

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