The aromatase inhibitor, exemestane, can reduce the spread of breast cancer by nearly a fifth, according to the TEAM (Tamoxifen and Exemestane Adjuvant Multicentre) trial.
Marketed as Aromasin, the hormone therapy drug works by stopping production of the female hormone, oestrogen, which fuels most breast cancer tumours.
A previous study shows that switching to exemestane reduces the risk of dying by 17%, while women who received the treatment were 19% less likely than those receiving standard treatment to suffer metastatic cancer. There was a 17% lower incidence of new tumours.
Dr Daniel Rea, Consultant in Medical Oncology at University Hospital Birmingham, who led the UK arm of the TEAM trial, said: "TEAM convincingly demonstrates that distant recurrence, a feared outcome after surgery, is reduced in the first few years after diagnosis when Aromasin is used initially instead of tamoxifen."
The drug is currently not licensed for initial therapy in the UK. The new findings were presented at the San Antonio Breast Cancer Symposium in Texas.