Scientific breakthrough could defuse breast cancer ‘ticking time bomb’

• 44,000 Britons and 210,000 Americans are diagnosed with ER+ breast cancer each year
• They remain at risk of recurring cancer in another part of their body for decades
• Researchers have now discovered a mechanism triggering this ‘time bomb’ against cancer

Researchers have discovered why breast cancer cells that have spread to the lungs can wake up after years of sleep and form incurable tumours.

About 44,000 Britons and 210,000 Americans are diagnosed each year with the most common type of breast cancer – estrogen receptor positive (ER+).

These patients remain at risk of their cancer recurring in another part of their body for decades after their initial diagnosis, even after successful treatment.

Now experts have discovered the mechanism that triggers this cancer ‘ticking time bomb’ in the lungs, one of the most common places where cancer can spread.

And an existing cancer drug can slow the growth of these secondary tumors, their mouse study suggests.

Patients with ER+ breast cancer remain at risk of cancer cells surviving dormant in their organs for years after treatment ends.

In order to understand the signals that trigger the action of these cells and the formation of tumours, researchers at the Institute for Cancer Research (ICR) in London studied mice with ER+ breast cancer who underwent scanners.

The findings, published in the journal Nature Cancer, suggest that molecular changes in the lungs encourage the growth of secondary tumours.

The PDGF-C protein, which is vital for tissue growth and survival, plays a key role in determining whether inactive breast cancer cells stay asleep or “wake up”.

As protein levels increase, which happens due to aging or when lung tissue is damaged or scarred, dormant cancer cells can grow and develop into secondary breast cancer in the lungs.

The researchers then explored whether blocking PDGF-C activity could help prevent these cells from “waking up”.

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They gave mice an existing cancer growth blocker called imatinib, which is currently used to treat patients with chronic myeloid leukemia.

Mice were treated with the drug before or after tumor development.

Among both groups, cancer growth in the lung was significantly reduced, according to the study funded by Breast Cancer Now.

Study author Dr Frances Turrell, a postdoctoral fellow in the Division of Breast Cancer Research at ICR, said: “We have discovered how aging lung tissue can trigger the ‘awakening’ of these cancerous cells and their development into tumors and discovered a potential strategy to “defuse” these “ticking time bombs”.

“We now plan to better determine how patients might benefit from the existing drug imatinib and, in the long term, aim to create more specific treatments targeting the ‘wake-up’ mechanism.

Rachel Davies, 38, who lives in Swansea, was diagnosed with ER+ breast cancer in 2021 and underwent mastectomy, lymph node removal, chemotherapy and radiotherapy.

Following a scan in May 2022, three months after treatment ended, she was told the cancer had spread to her sternum and later to her spine. She is now receiving a targeted cancer drug called ribociclib and hormonal therapy.

Ms Davies said: ‘I’ve seen women finish treatment and ring that bell and celebrate its end, and that always worries me because you can never be satisfied it doesn’t come back.

“Finding out the cancer had spread when I thought it was all in the past was heartbreaking.

“That’s why it’s so important that secondary breast cancer research happens so we can find new ways to stop women going through what I’m going through.”

She added: “Research like this gives me hope for women being treated for breast cancer in the future. I don’t want to waste my precious time being bitter or angry.

Professor Clare Isacke, Professor of Molecular Cell Biology at the ICR and co-author of the study, said: ‘This is an exciting advance in our understanding of advanced breast cancer – and how and why cancer cells in the breast form secondary tumors in the lungs.

“Next, we need to determine when these age-related changes occur and how they vary from person to person, so we can create treatment strategies that prevent cancer cells from ‘waking up’.”

Dr Simon Vincent, Director of Research, Support and Influence at Breast Cancer Now, said: “This exciting discovery brings us closer to understanding how we can slow or stop the development of secondary breast cancer. ER+ in the lung.

“It has the potential to benefit thousands of women living with this ‘ticking time bomb’ in the future, ensuring that fewer patients receive the devastating news that the disease has spread.”