Women with hereditary breast cancer, triggered by the BRCA1 or BRCA2 genes, stand a better chance of survival following successful trials of a drug that cuts the likelihood of the cancer returning after treatment.
A major trial carried out by academic researchers to see whether olaparib can prevent recurrence was stopped early – after two-and-a-half years instead of the planned 10 years – when the benefits of the drug became clear.
The results, published in the New England Journal of Medicine and presented online at the American Society of Clinical Oncology conference, showed it reduced the relative risk of invasive recurrence, second cancers or death by over 40%.
In absolute terms, 85.9% of women given olaparib in pill form for a year after the end of their treatment remained alive with no return of their cancer for three years, compared with 77.1% on a placebo. The difference was similar when it came to metastatic disease, which is cancers occurring in other places in the body – 87.5% on olaparib and 80.4% on a placebo.
Out of 921 patients on olaparib, 106 had a recurrence of invasive cancer or died by three years, compared with 178 (of 915) patients on a placebo.
“In curative therapy trial terms, this is a really major result,” said Prof Andrew Tutt from the Institute of Cancer Research in London, who led the international trial.
For every 100 women treated, it meant, he said, “an extra nine women – let’s say eight or nine women – who are alive and well, without evidence of a recurrence of breast cancer, or the development of any other cancer”.
Until this trial, there was nothing to help women with the inherited breast cancer genes – who are often young and suffer from the most severe forms of cancer – who feared their cancer would return.
“Every year, thousands of women in the UK are diagnosed with hereditary breast cancer caused by an altered BRCA gene,” said Dr Simon Vincent, director of research at the charity Breast Cancer Now. “Finishing active hospital treatment can be an incredibly difficult time, with many women calling our helpline to share their anxiety and fears of their breast cancer coming back. So finding effective new ways to prevent recurrence is vitally important.
“It’s extremely exciting that this groundbreaking study could pave the way for a targeted treatment for women with high-risk HER2 negative primary breast cancer with altered BRCA genes, preventing recurrence and potentially helping to stop women dying from this devastating disease. Olaparib must now be promptly submitted for licensing and then assessed for use on the NHS, so that women with this type of breast cancer start to benefit from this new discovery as soon as possible.”
Olaparib works by stopping cancer cells from being able to repair their DNA by inhibiting a molecule called PARP, causing cancer cells to die. It works particularly well for patients with faulty versions of the BRCA1 or BRCA2 genes, which are normally involved in another system for repairing DNA. In the trial, significant side-effects were reported to be relatively infrequent.
The drug is already licensed for use in treating genetic forms of breast, ovarian, prostate and pancreatic cancers, although it is expensive and not yet available on the NHS. The researchers hope their study will help speed up a licence for olaparib that will enable all women who have recovered from hereditary breast cancer to take it.