Preventative cancer therapies can cause the disease to ‘hibernate’ and return later, research suggests

Preventative treatment designed to stop the recurrence of breast cancer can actually cause the cancer cells to mutate and ‘hibernate’, only to grow again years later, according to new findings.

Researchers who set out to explain why breast cancer can return years after initial treatment have found that hormone therapies, used to prevent breast cancer from recurring, can trigger changes in some cells.

These changes cause the cells to lie dormant instead of dying off, and the cells then “wake up” years later, causing a relapse that is harder to treat.

But the study found there may be a way to target these “sleeping” breast cancer cells before they “wake up”, offering new hope for patients with oestrogen receptor positive (ER+) breast cancer – which makes up 80% of all breast cancers.

Luca Magnani, professor of epigenetic plasticity at The Institute of Cancer Research, London, said: “After surgery to remove primary oestrogen receptor positive breast cancer, patients are given five to 10 years of hormone therapy which aims to kill any remaining cancer cells.

“We know that this doesn’t work for all patients though, as their breast cancer can return years, or even decades later.

“We wanted to better understand why breast cancer does return so we can hopefully find ways to stop it – so people don’t have to live in fear or face the devastating news of a relapse.