A new treatment option is more effective than tamoxifen at preventing a return of breast cancer in young women, according to the results of two international trials.
The findings show that exemestane, given along with treatment to suppress the function of the ovaries, reduced the risk of breast cancer's return by 34 per cent, and cut the risk of a subsequent invasive cancer by 28 per cent.
Exemestane is an aromatase inhibitor that until now has largely been used in older women who have reached menopause, since it requires women to have a low level of oestrogen in order to work.
Tamoxifen, meanwhile, is commonly prescribed to women who have had breast cancer as a way to prevent its return.
"For years, tamoxifen has been the standard hormone therapy for preventing breast cancer recurrence in young women with hormone sensitive disease," said lead study author Olivia Pagani, clinical director of the breast unit at the Oncology Institute of Southern Switzerland.
"Our findings indicate that exemestane is better than tamoxifen, when given with ovarian function suppression. But longer follow up of these young women will be important to assess survival and any long-term side effects and fertility."
The results were presented at the American Society of Clinical Oncology conference. They showed the joint analysis of two trials, including a total of 4,690 women, average age 43, who were randomised to receive either tamoxifen plus ovarian suppression therapy or exemestane plus ovarian suppression therapy.
The cancer-free survival in the exemestane group was 91.1 per cent, compared to 87.3 per cent in the tamoxifen group.
"Tamoxifen has been a gold standard for decades and has significant benefits," said ASCO president Clifford Hudis.
"Now, with ovarian suppression, aromatase inhibitors are an option offering further reduction in the risk of recurrence."