The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has authorised a new indication for anastrozole, to prevent breast cancer in post-menopausal women at moderate or high risk of developing the disease.
The hormone treatment was already authorised for use in the treatment of breast cancer in post-menopausal women and has been used off-label for prevention.
Evidence for the label extension was based on the IBIS-II study, an international, randomised double-blind, placebo-controlled trial, which showed fewer women developed breast cancer in the anastrozole group compared to the placebo group.
Anastrozole is an aromatase inhibitor, which works by cutting down the amount of the hormone oestrogen that a patient’s body makes by blocking an enzyme called ‘aromatase’.
The IBIS-II trial showed that anastrozole is more effective than tamoxifen in preventing the return of cancer in post-menopausal women who have an early breast cancer removed. In these women it reduces their risk of developing a new cancer in the opposite (contralateral) breast by 53% compared to tamoxifen.
Of the 3864 participants, there were 40 cases of breast cancer reported in the anastrozole group compared with 85 in the placebo group.
The data also showed that women on anastrozole were less likely to develop other cancers, with 40 cases being found in women taking anastrozole compared with 70 reported in the placebo group.
Anastrozole was shown to have fewer serious side effects than tamoxifen, though it can hot flushes, vaginal dryness and an slightly increase risk of osteoporosis.
Diana Spencer, Senior Digital Content Editor, DDW
