The National Institute for Health and Clinical Excellence (Nice) has banned another breast cancer drug from routine NHS use.
Cancer charities have greeted the move with disappointment and said drugs of this type are "particularly valuable".
The drug fulvestrant (known commercially as Faslodex and manufactured by AstraZeneca) is used to delay the growth of a certain type of breast cancer and has previously been rejected for other types of breast cancer.
But Nice's draft guidance said it does not believe the evidence submitted by the drug's manufacturer proves it works significantly better than existing treatments and so its widespread use would not be a good use of resources.
The body said the evidence that fulvestrant could extend a patient's life compared to using alternatives was ‘considerably uncertain' and while it was shown to delay cancer growth better than one competitor, there was no evidence that it was better than another.
Nice also estimated that the £35,000 cost per quality-adjusted life years measurement gained from fulvestrant was above its guideline acceptance range of £20,000 - £30,000.
Sir Andrew Dillon, chief executive of NICE, said: "While there is evidence that fulvestrant can delay the growth of breast cancer, our independent committee found when used according to its marketing authorisation, its effectiveness is uncertain compared to aromatase inhibitors, which are currently the preferred treatment options on the NHS.
"NICE has to ensure that the NHS provides treatments that bring benefits which are value for money.
"As fulvestrant has not been proven to be cost-effective, we cannot justify diverting NHS funds from other areas of healthcare in order to fund its use," he added.
Maria Leadbeater, clinical nurse specialist at Breast Cancer Care, explained the charity's disappointment and feared it would shrink an already small number of treatment options.
"The decision by NICE not to recommend the routine prescription of fulvestrant by the NHS for post-menopausal women with locally advanced or secondary breast cancer is disappointing news for patients and their families," she said.
"While we recognise that drug decisions must be based, to some degree, on cost effectiveness, this approach can fail to take into account what is important for the patient.
"Treatment options for people living with secondary breast cancer are limited, so any drugs which delay time to progression are especially valuable.
"We do, however, welcome the acknowledgement of the importance of additional treatment options for this patient group," she added.
Those women currently being treated with fulvestrant will be able to remain on the drug until they or their consultant considers it appropriate to stop.
