Issuing its final draft guidance on the matter, the National Institute for Health and Clinical Excellence (Nice) said they were not convinced of the benefits of using Tyverb or Herceptin in conjunction with hormone drug therapies known as aromatase inhibitors.
Sir Andrew Dillon, Nice's chief executive, said: "Unfortunately the manufacturers of lapatinib (Tyverb) and trastuzumab (Herceptin) didn’t give our independent committee convincing evidence to show how much using either drug with an aromatase inhibitor could benefit these women, more than using the aromatase inhibitors by themselves."
He added: "The cost effectiveness of the drugs was also significantly uncertain."
Although Nice accepted evidence that using Tyverb in conjunction with letrozole increased the amount of time that patients' cancer did not advance by five months, it also noted that overall survival was not significantly lengthened.
It found the cost per average patient for Tyverb was £27,336, which would buy 55 weeks' supply; while it was £24,852 for Herceptin, which could buy 15 months' supply.
Meg McArthur, from Breakthrough Breast Cancer, said: “There is a real need for more targeted and effective treatment options for this small group of breast cancer patients.
"It’s vital to find the right drug combinations for the right patients and we’ll continue to work with Nice to ensure high quality treatment and care is available for all NHS breast cancer patients.
"We encourage anyone who is concerned about their treatment options to speak to their doctor.”
Simon Jose from GSK, which makes Tyverb, said the company was "naturally disappointed" with the decision.
The firms or other interested groups can now only appeal on a legal technicality. They have until July 15 to do so.