A Sheffield expert is calling for a 43p-a-day drugs to be made available to women battling breast cancer.
Rob Coleman, professor of medical oncology at the University of Sheffield, spoke out after research found that thousands of women with postmenopausal breast cancer are missing out on lifesaving drugs that could prevent their disease spreading.
A poll of cancer specialists for the charity Breast Cancer Now found confusion over who funds bisphosphonates - cheap drugs typically used to treat osteoporosis.
The drugs alter bone tissue, making it harder for cancer cells to survive there, and are already used for patients with advanced prostate cancer.
They have been hailed as having the potential to prevent around one in 10 breast cancer deaths.
But Breast Cancer Now calculates that around 27,000 women every year are missing out on bisphosphonates, with the main reason cited being a lack of clear guidance on who should fund them.
Its poll, which involved responses from 125 cancer specialists, nearly half said were waiting for funding decisions before prescribing the drugs.
Professor Coleman, from 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."
Baroness Delyth Morgan, chief executive at Breast Cancer Now, has called for a national policy on who would fund the drugs.
She said: "While bisphosphonates are not routinely available to all eligible breast cancer patients, women's lives are 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.
"But they are still sitting on the shelf, blocked by bureaucratic inertia.
"We're fortunate to have so many of the world's leading oncologists working within the NHS, and we must ensure they have all the tools they need to offer the best possible breast cancer treatment."
NHS England said decisions on the funding of the drugs were currently made locally