The drug targets the hormone oestrogen
A class of breast cancer drug currently used once the disease has spread, should also be used in the early stages, the NHS advisory body proposes.
Preliminary guidance from the National Institute for Health and Clinical Excellence backs widespread use of aromatase inhibitors.
Trials showed they were more effective for some women than current treatments.
Campaigners said the move would offer women more choice, but a final decision is not expected until November.
Aromatase inhibitors stop the natural production of oestrogen - the hormone responsible for many breast cancers.
The draft guidance comes after it has already been made available on a restricted basis in Scotland, where it has been approved for post-menopausal patients after they have been treated with tamoxifen.
The NICE guidance states that it should be used alongside tamoxifen, the current 'gold standard' treatment, on post-menopausal women with early oestrogen-receptor-positive invasive breast cancer.
In one trial, the inhibitors proved to be a fifth more effective at preventing breast cancer than tamoxifen.
Other tests showed it could be used after taking tamoxifen to further reduce the risk of the disease coming back.
Three aromatase inhibitors are set for tentative approval - anastrozole, exemestane and letrozole.
They cost about £1,000 per patient per year - ten times more than tamoxifen.
They could benefit around 20,000 women in the UK.
Jeremy Hughes, chief executive of Breakthrough Breast Cancer, said: "The current 'gold standard' treatment tamoxifen has already had a big impact on women's lives.
"These new treatment options will be an important addition to the armoury of therapies available to treat women with the disease.
"They could make a real difference in reducing the risk of breast cancer returning and increasing disease-free survival."
He added that NHS trusts should make the drug available for some patients on the basis of this draft recommendation.
Professor John Toy, medical director of Cancer Research UK, said he had high hopes for the treatment.
"Cancer Research UK is delighted that NICE is recommending that aromatase inhibitors, the next improved generation of treatments after tamoxifen, should become available for the NHS."
Joanne Rule, of the charity Cancerbackup Chief Executive, welcomed the preliminary decision.
She added: "Until full approval is given by NICE it is important to remember that if a women and her clinician decide that a certain treatment is suitable, there is nothing to prevent Primary Care Trusts from prescribing it as they do not need to wait for NICE guidance."