Drugs used to treat the bone condition osteoporosis could prevent 1000 breast cancer deaths a year, according to a large analysis of previous clinical trials.
The study published in The Lancet, showed that the drugs – called bisphosphonates – reduced the risk of breast cancer coming back, as well as significantly reducing the risk of death, in women diagnosed after their menopause with early-stage breast cancer.
Breast cancers most commonly spread to the bone, and treatment with bisphosphonates alters the bone tissue. This potentially makes the bone a more challenging environment for rogue cancer cells to survive in, reducing the risk of the cancer coming back.
To test this, the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) set up by researchers at the Nuffield Department of Population Health,University of Oxford, alongside collaborators from Oxford University Hospitals NHS Trust and many other institutes, combined data from 18,766 women from 26 clinical trials, comparing women who took bisphosphonates for between two and five years, with those who had no bisphosphonates.
Postmenopausal women on bisphosphonates saw a 28 per cent reduction in the chances of their cancer coming back. Bisphosphonates also reduced the risk of dying from the disease during the first 10 years after diagnosis by 18 per cent.
Professor Robert Coleman, who led the study, said that the results show that giving postmenopausal women bisphosphonates after surgery could “prevent around a quarter of bone recurrences and one in six of all breast cancer deaths in the first decade of treatment”.
Cancer Research UK’s chief clinician, Professor Peter Johnson, said that while findings had the potential to save many lives, further in-depth research will be needed.
“This large analysis suggests that, if post-menopausal women with early breast cancer were given bisphosphonates after surgery, it could stop cancer spreading to their bones and save around 1,000 lives a year,” he said.
“Many women already get bisphosphonates to protect against bone disease, but before doctors give this drug to all post-menopausal women at high-risk of breast cancer, more thorough clinical trials are needed,” he added.
A second study by the EBCTCG, also published in The Lancet, looked at the effectiveness of different hormone therapies for breast cancer.
It’s results provide further support for recommendations by NICE that hormone therapies called aromatase inhibitors should be offered to women with early-stage oestrogen receptor (ER)-positive breast cancer, over an older hormone therapy called tamoxifen.
Researchers found that women with ER-positive breast cancer taking aromatase inhibitors for five years had a 40 per cent lower risk of dying within 10 years of starting treatment, compared to those who didn’t take hormone therapy.
This compared to a 30 per cent lower risk following five years of treatment with tamoxifen.
Aromatase inhibitors work by preventing the body from producing oestrogen, and are taken by postmenopausal women with ER-positive breast cancer. They have previously been shown to be more effective than tamoxifen in reducing the chances of cancer coming back, but the new study is the first to show a greater reduction in death rates.
The study looked at data from 31,920 women across nine international clinical trials, with each study including women who had been treated with aromatase inhibitors or tamoxifen at various times during the study.
Lead author Professor Mitch Dowsett, from The Royal Marsden and The Institute of Cancer Research, London, said the global research effort confirmed that aromatase treatment provided “significantly greater protection than that offered by tamoxifen”.
But he cautioned that aromatase therapy was not without its side-effects.
“Aromatase inhibitor treatment is not free of side-effects, and it’s important to ensure that women with significant side-effects are supported to try to continue to take treatment and fully benefit from it,” he said.
The power of such long-term analyses was welcomed by Professor Paul Workman, Chief Executive of The Institute of Cancer Research, London, who said they were crucial for bringing the best treatments to patients.
“It tends to be the discovery of new treatments that grabs the headlines, but it is just as important to maximise the benefit patients get from existing treatments, through major, practice-changing studies like this,” he said.
Both studies were funded by Cancer Research UK and the Medical Research Council.
- Early Breast Cancer Trialists’ Collaborative Group: Adjuvant bisphosphonate treatment in early breast cancer: meta-analyses of individual patient data from randomised trials. Lancet (2015) DOI:10.1016/ S0140-6736(15)60908-4
- Early Breast Cancer Trialists’ Collaborative Group: Aromatase inhibitors versus tamoxifen in early breast cancer: patient-level meta-analysis of the randomised trials. Lancet (2015) DOI:10.1016/S0140-6736(15)61074-1