Thousands of post-menopausal women with breast cancer are missing out on cheap drugs that could prevent their disease spreading, research suggests.
A survey by Breast Cancer Now found there was confusion over who funded bisphosphonates, normally used to treat the bone disease osteoporosis.
One in 10 deaths from breast cancer could be avoided if they were given to all eligible women, it said.
The drugs have been shown to cut the risk of cancer spreading to the bone.
Bisphosphonates were originally licensed to treat bone fractures in adults with advanced breast cancer.
But a study published in The Lancet last year found the drugs could also help women treated for early breast cancer after the menopause.
They were shown to reduce the risk of breast cancer spreading to the bone by 28% and the risk of dying from breast cancer by 18% after 10 years.
The drugs are estimated to cost 43p on average per day per patient and can be taken for about three years.
However, charity Breast Cancer Now says thousands of women are potentially missing out on taking these inexpensive drugs because of the lack of national guidance on who should fund them.
The charity says it is not clear whether the hospital trust, the local clinical commissioning group (CCG) or NHS England central funding should be paying for them.
In a survey of 125 breast cancer doctors by the UK Breast Cancer Group, less than a quarter said they could routinely offer the drugs to their patients.
Baroness Morgan, chief executive at Breast Cancer Now, said women’s lives were needlessly being put at risk.
“These are cheap and widely available drugs, and the overwhelming evidence of their ability to save lives should have changed practice by now,” she said.
“But they are still sitting on the shelf, blocked by bureaucratic inertia.”
Baroness Morgan called on the NHS to give clear guidance on how the drugs were funded, in order to offer the best possible cancer treatment.
The charity said prescribing the drugs to all eligible patients – potentially an extra 27,000 women – could save the NHS money in the long term because these patients would no longer need bone density scans and fewer would go on to develop secondary breast cancer.
Prof Rob Coleman, professor of medical oncology at the University of Sheffield, said: “It should be an absolute priority for every clinician and commissioner involved in the provision of breast cancer services to ensure this simple and safe treatment is made available, as a matter of urgency.”
NHS England said decisions on the funding of bisphosphonates were currently made locally but it was awaiting new guidelines from the National Institute for Health and Care Excellence (NICE).
These guidelines, on the diagnosis and management of early and locally advanced breast cancer, are expected to be published in July 2018.