Studies show AI's and Bisphosphonates increase survival

New research from two studies has found postmenopausal patients with early stage breast cancer who take two types of drugs, aromatase inhibitors (such as Letrozole or Anastrozole) together with bisphosphonates, have better survival rates than those who don’t. 

Results from the two studies were collated by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) group in the UK and published recently in The Lancet medical journal.

An aromatase inhibitor (AI) is a drug that stops estrogen production in postmenopausal women meaning less estrogen is available to stimulate the growth of hormone-receptor positive breast cancer cells. 

The first study, which gathered evidence from 30,000 postmenopausal women in nine clinical trials, showed that five years of treatment with an AI reduced the chances of the cancer returning by almost one-third compared with patients who had standard endocrine treatment such as Tamoxifen. The risk of dying from breast cancer was reduced by approximately 15% in the decade following treatment for those who took an AI compared with those taking Tamoxifen and a 40% reduction in risk of dying compared with those who had no endocrine treatment. 

The second study, which brought together evidence from 20,000 women in 26 clinical trials, showed that 2-5 years of treatment with bisphosphonates also reduced the risk of breast cancer recurrence and extended survival in postmenopausal women. A bisphosphonate is a type of drug that prevents the loss of bone mass and is typically used to treat osteoporosis. It is often prescribed to women taking an AI as a common side effect of AI’s is a loss of bone density. 

One of the most common sites where breast cancer is likely to spread to is in the bone. Taking a bisphosphonate to maintain and increase bone density has been shown to alter the bone microenvironment thus making it less favourable for cancer cells to grow. 

The study showed a 28% reduction in recurrence of cancer in the bone and reduced the risk of dying from breast cancer in the decade after treatment by 18% in postmenopausal women. However, for pre-menopausal women, bisphosphonate treatment appeared to have little effect on their survival rates. 

Breast Cancer Aotearoa Coalition, Deputy Chair, Chris Walsh, said it was pleasing to see these results and reassuring for women to know that taking these treatments would lessen their chances of a recurrence and improve their survival chances long term. “Breast cancer patients always worry about the possibility of their cancer returning and spreading so this will be added reassurance for them.”

27 August, 2015

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