Women with breast cancer who take common blood pressure drugs may have better odds of surviving the disease, two studies have found.
In one study, women taking beta-blockers survived longer without seeing the tumour return than those not on the medication. In the other, they were less likely to be diagnosed with aggressive breast cancer or die from it.
‘We saw an association, now it’s time to prove whether they are the cause,’ said Dr Amal Melhem-Bertrandt, who worked on one of the studies.
‘It’s very promising, it’s encouraging, but we still have to do the studies.’
Beta-blockers curb the effect of stress hormones like adrenaline and noradrenaline, and are used to treat high blood pressure.
Cancer researchers began to take an interest in them after animal studies showed stress responses are linked to tumor growth.
‘There is a lot of literature suggesting chronic stress may influence breast cancer recurrence,’ Dr Melhem-Bertrandt said.
‘We wanted to see whether blocking one of the arms of your stress response would help reduce breast cancer.’
She and her colleagues looked at medical records for 1,400 women treated for breast cancer with chemotherapy and surgery at the M.D. Anderson Cancer Center in Houston. About seven per cent of the women also happened to be taking beta-blockers.
Breast cancer
The doctors who examined the tumors after the women had surgery found no differences between those who were on beta-blockers – mainly metoprolol and atenolol – and those who weren’t.
However, the women on beta-blockers did seem to fare better afterward. At three years, 87 per cent of them were alive and cancer-free, compared to 77 per cent of those not taking the drugs.
Results were better with beta-blockers even after the researchers accounted for differences in age, cancer stage, diabetes and other factors that might influence tumor growth.
And the findings were even more striking for women with so-called triple-negative breast cancer, which doesn’t respond to hormone therapy.
‘We used to think of these drugs as innocent bystanders, but it looks like they may have an effect on cancer itself,’ said Dr Melhem-Bertrandt.
Still, hidden factors could be at play, such as lifestyle or medication differences between the women, Dr Melhem-Bertrandt cautioned.
What’s more, her study wasn’t large enough to show a potential effect on overall survival.
Breast cancer
In recent work from the Trinity Centre in Dublin, researchers found similar survival rates among breast cancer patients taking beta-blockers and those taking other blood pressure medications.
‘Larger studies are needed to clarify the effect of beta-blockers on breast cancer outcomes,’ said Dr Sunil Shah, of St George’s University of London, who worked on the UK study.
‘But, if these benefits are confirmed, these findings are potentially important for a sub-group of women with breast cancer as beta-blockers are a relatively safe and inexpensive therapy,’ she added.
The other new study, published along with Dr Melhem-Bertrandt’s results in the Journal of Clinical Oncology, tapped into data from a cancer registry and a pharmacy database in Ireland.
Women with breast cancer who were taking a type of beta-blocker called propranolol were much less likely to be diagnosed with advanced breast cancer than closely matched patients not on the drugs, according to Dr Thomas Barron from Trinity Centre for Health Sciences in Dublin, Ireland.
Women taking propranolol also fared better after being diagnosed with the disease: After five years, an estimated nine per cent had died of breast cancer, compared to 27 per cent of women not on propranolol.
There was no such difference for atenolol, another beta-blocker, however. That contradicts Melhem-Bertrandt’s findings, and suggests not all beta-blockers work the same.
With this much uncertainty, Melhem-Bertrandt said, beta-blockers aren’t ready for prime time yet in the breast cancer world.
‘They do have side effects,’ she said.
‘They can drop your blood pressure, they can slow your heart rate. I would not recommend women go on beta-blockers as a preventive measure.’
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Around one in six women have triple-negative cancers that don’t respond to most treatments
A network of overactive genes drives one of the deadliest forms of breast cancer, scientists said today.
The discovery could lead to new therapies for ‘triple-negative’ cancers, which affect around one in seven women with the disease and fail to respond to most treatments.
Studies have already shown that drugs designed to target the genes can stop breast tumours growing in mice.
It should be possible to test the drugs on breast cancer patients soon as they are already at advanced stages of clinical testing for blood cancers linked to the same pathway.
Geneticist Dr Kornelia Polyak, from the Dana-Faber Cancer Institute in Boston, U.S, said: ‘The discovery of these targets will rapidly lead to clinical trials with the hope of achieving one of the first specific therapies for triple-negative breast cancers.’
The research is reported today in the Journal of Clinical Investigation.
Triple-negative breast cancers lack molecular “receptors” that allow them to be stimulated by the hormones oestrogen and progesterone, and the protein HER2.
They cannot therefore be treated with breast cancer drugs that work by blocking the receptors.
Such tumours make up an estimated 15 per cent to 20 per cent of breast cancers. They tend to occur in younger women, black women, and women carrying BRCA1 gene mutations.
Previous research by Dr Polyak showed that triple-negative tumours contain large numbers of immature “stem-like” cells which constantly renew themselves and help cancer to spread.
Laboratory experiments showed that many of the tumour cells displayed increased activity in a network of genes called the Jak2/Stat3 pathway.
The scientists identified 1,576 genes that differed from those in less dangerous cancer cells.
From these, 15 were singled out that appeared to be necessary for tumour growth and could be promising drug targets.
By blocking the activity of several genes, the researchers were able to suppress cell growth.
Inhibiting drugs existed for five of the genes identified in the network, two of which were currently in advanced clinical trials.
The abnormal pathway is likely to be present in half of patients with triple-negative breast cancer, said the scientists.
Dr Caitlin Palframan, from the charity Breakthrough Breast Cancer, said: ‘This research is very exciting as new treatments for triple-negative breast cancer are urgently needed.
‘There are limited treatment options available for this group of patients so a targeted treatment would be a real breakthrough.
‘However, this is early stage research in mice and we look forward to seeing if this approach will prove effective in the upcoming clinical trials.’
A team of the charity’s scientists from King’s College London is currently conducting research aimed at identifying factors driving the growth of triple-negative breast cancer.