A low-cost blood pressure medication, currently taken by millions, may offer protection against a highly lethal type of breast cancer, according to recent findings.

Researchers from Monash University in Melbourne have discovered that beta blockers, which minimize the impact of stress hormones, might also impede the advancement of triple negative breast cancer in certain patients.

The link between beta blockers and breast cancer first emerged in 2023, though it was not clear why. 

Now, researchers believe they have identified the mechanism—and with it, a potential low-cost treatment for an extremely aggressive disease.

The study focused on how two signaling molecules, cAMP and calcium, promote the spread of cancer when a receptor known as the beta-2 adrenoceptor is triggered.

Stress hormones such as cortisol can trigger this receptor, fuelling tumour growth.

But the team has now discovered that beta blockers can switch off a gene—HOXC12 —which drives this process, slowing the progression of the disease.

This breakthrough could enable medical professionals to determine, right at the time of diagnosis, which patients might gain the most from beta blocker treatment.

Professor Michelle Halls, who led the research and is an authority in drug discovery biology at the Monash Institute of Pharmaceutical Sciences, remarked that the findings are thrilling as they validate the possible connection between beta blockers and cancer progression.

‘Our colleagues previously found that beta blockers are associated with a significant reduction in mortality in people with triple negative breast cancer. 

‘Now we have a much better grasp on why this could be the case,’ she said.

Mr Terrance Lam, a pharmaceutical PhD candidate at the institute and co-author, added: ‘Our collective research strongly suggests that HOXC12 is a potential new indicator for when triple negative breast cancer patients could respond to beta blocker targeted interventions. 

‘Triple negative breast cancer is an aggressive cancer which can be especially challenging to treat and identifying new treatment pathways are important.’

The researchers are now calling for further studies to ‘urgently’ determine whether the gene can be used at diagnosis to identify patients who will benefit from beta blocker therapy—and stop their cancer spreading.

Beta blockers, commonly prescribed to lower blood pressure, work mainly by slowing the heart and blocking the action of stress hormones such as adrenaline. 

According to the study, published in Science Signaling, there is a strong correlation between activation of the beta-2 adrenoceptor and accelerated cancer spread.

They also found that patients with high levels of HOXC12 expression in women with this form of cancer were associated with poorer overall survival outcomes .

One in seven women in the UK are diagnosed with breast cancer in their lifetime—around 56,000 a year—making it the most common cancer in the UK. 

Around 85 per cent of women diagnosed with breast cancer survive for more than five years following their diagnosis. 

However, triple negative breast cancer—which accounts for around 15 per cent of all breast cancers in the UK and US—is far more challenging to treat. 

Typically, it grows and spreads faster than other breast cancer types and has fewer treatment options. 

One reason for this is because it doesn’t interact with hormones such as oestrogen in the same way as other breast cancers—for which there are targeted therapies. 

On average around 77 per cent of women with triple negative breast cancer will survive their cancer for five years or more after they are diagnosed, but depending on the stage this can fall as low as 12 per cent. 

This is compared to around 90 per cent of women with other forms of breast cancer who will survive for at least five years.