A hormone-blocking drug could save many breast cancer patients from undergoing a mastectomy, a study has shown. The drug anastrozole, or Arimidex, reduced or completely shrunk breast tumours in 50% of women involved in a clinical trial. It was also found to be more effective than the usual drug of choice tamoxifen in reducing the size of breast cancer tumours. The study was conducted by drug company AstraZeneca, who manufacture Arimidex. The study findings coincide with the release of a separate survey of 500 women by NOP Research. This found most women feared losing a breast if diagnosed with breast cancer.