In patients with triple-negative breastcancer, a form of the disaese that responds to few existing drugs, none of the patients in the control group had a response.
On Friday the drug was approved for use in combination with Aromasin for postmenopausal women with recurring HER2-negative breastcancer, after treatment with the drugs Femara and Arimidex.
Campaigners feared it would have a negative impact on the quality of breastcancer care on the island, but the Royal College of Surgeons supported the move.
She said she recently treated a woman whose breastcancer initially tested negative for a mutation that causes elevated levels of a cancer-promoting protein called HER2, which would have made her a candidate for the drug Herceptin.
In fact, it is likely that only a small proportion of hereditary cancers have a link to the BRCA gene, so a negative result could never rule out even hereditary breastcancer.
Lead researcher Dr Ronit Peled, from Ben-Gurion University, said that women who had been exposed to a number of negative events should be considered an "at-risk" group for breastcancer.