Breast Cancer Survival Improved by 2 Drug Classes

Two different classes of drugs, aromatase inhibitors (AIs) and bisphosphonates, may be able to reduce breast cancer mortality among postmenopausal women, according to results from a pair of studies recently published in the Lancet.

The first study evaluated the effectiveness of AIs in approximately 30,000 postmenopausal women across 9 randomized trials. Compared with 5 years of standard endocrine therapy (tamoxifen), 5 years of treatment with AIs was found to have reduced the likelihood of cancer recurrence by 30% and the risk of dying of breast cancer by 15%. The study authors also estimated that the use of AIs reduced death cancer mortality by about 40% compared with no endocrine treatment.

The second study assessed the effectiveness of bisphosphonates in 18,766 women across 26 randomized trials. Compared with no bisphosphonate, 2 to 5 years of treatment with bisphosphonate was associated with a 28% reduction in recurrence of bone cancer and an 18% reduced risk of breast cancer mortality among postmenopausal women. However, bisphosphonate treatment did not appear to reduce the likelihood of breast cancer developing in the opposite breast, nor did it seem to have a significant effect in premenopausal women.

“The drugs are complementary, because the main side effect of aromatase inhibitors is an increase in bone loss and fractures, while bisphosphonates reduce bone loss and fractures as well as improv[e] survival,” said Richard Gray, MA, MSc, the lead statistician for both studies, in a press release.