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August 5, 2015
AI, Bisphosphonate Combo Effective in Postmenopause
Breast Cancer

London, England—Two different classes of drugs, aromatase inhibitors (AIs) and bisphosphonates, improve survival prospects for postmenopausal women with early breast cancer better than some more expensive therapies, according to a new study.

Two studies, published recently in The Lancet, also point out that the drugs can be used together, both increasing benefits and decreasing some side effects.

The research was performed by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), a worldwide collaboration established 30 years ago by researchers at the University of Oxford in the UK. Investigators point out that the study offers the best evidence yet for the positive effects of AIs and bisphosphonates on postmenopausal women with early breast cancer.

“Our global collaboration has revealed that the risk of postmenopausal women with the most common form of breast cancer dying of their disease is reduced by 40% by taking five years of an aromatase inhibitor—a significantly greater protection than that offered by tamoxifen,” explained the AI study’s lead author Mitch Dowsett, FMedSci, PhD, of The Royal Marsden and The Institute of Cancer Research in London. “The impact of aromatase inhibitors is particularly remarkable given how specific these drugs are— removing only the tiny amount of estrogen that remains in the circulation of women after the menopause—and given the extraordinary molecular differences between ER-positive tumors.”

The AI study involves evidence from 30,000 postmenopausal women in nine randomized trials and concludes that 5 years of treatment with the aromatase enzyme suppressant produces somewhat better survival than 5 years of standard endocrine therapy with tamoxifen. Results indicate that, compared to tamoxifen, taking AIs for 5 years further reduced the likelihood of the cancer recurring by about 30%, and the risk of dying from breast cancer by around 15% in the 10 years after beginning treatment.

Compared to no endocrine treatment, the risk of dying from breast cancer for women who took AIs would be reduced by around 40% in the decade after beginning treatment, study authors assert.

The second study focused on another 20,000 women in 26 randomized trials, finding that 2 to 5 years of treatment with bisphosphonates reduced the risk of breast cancer recurrence and extended  survival in postmenopausal women, although they appeared to have little effect in premenopausal women.

In the overall study population, bisphosphonates’ only clear benefit was a 17% reduction in recurrence of cancer in the bone. Among postmenopausal women, however, bisphosphonate treatment produced a larger reduction in bone recurrence of 28% and also reduced the risk of dying from breast cancer by 18% during the first decade after diagnosis.

“Currently, bisphosphonates are mainly used to reduce bone loss and fractures in postmenopausal women and to reduce bone complications in advanced cancer patients,” said that study’s lead author Robert Coleman, MD, MBBS, of the University of Sheffield, recommending that the “simple, well tolerated treatments should now be considered for routine use in the treatment of early breast cancer in women.”



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