In postmenopausal women with early breast cancer, bisphosphonates in the adjuvant setting reduced the risk of recurrence in bone by 34% and breast cancer death by 17% according to a large meta-analysis conducted by the Early Breast Cancer Trialists’ Collaborative Group.
The risk reductions in bone recurrence and death with adjuvant bisphosphonates were observed in postmenopausal women regardless of estrogen receptor status, nodal status, and chemotherapy. Bisphosphonates had no effect on outcomes in premenopausal women.
“In addition to the 17% reduction in breast cancer–related mortality, adjuvant bisphosphonates led to an absolute reduction of 3.4% in all-cause mortality,” stated lead author Robert Coleman, MD, University of Sheffield, United Kingdom.
“These results are likely to be practice changing, leading to a new option for standard of care,” said Peter Ravdin, MD, who moderated a press conference at the San Antonio Breast Cancer Symposium at which these data were presented. Ravdin, who was not involved in the study, is the director of the Breast Health Clinic at the Cancer Therapy & Research Center of the University of Texas Health Science Center at San Antonio.
The large, individual patient meta- analysis was based on 36 randomized controlled trials with a total of 22,982 women that compared adjuvant use of bisphosphonate versus no bisphosphonate or placebo. Seven of the trials compared the bisphosphonate clodronate versus no bisphosphonate or placebo and 29 evaluated aminobisphosphonates versus no bisphosphonate or placebo (65% of the women taking aminobisphosphonates received zoledronic acid, 24% iban-
dronate, and 11% “other”).
In the overall trial, no significant difference was observed in the 10-year rate of all breast cancer recurrences or distant recurrences, including bone recurrences.
The effect of bisphosphonates was confined to 11,306 postmenopausal women (including women aged >55 years if menopausal status was unknown); bisphosphonates achieved a highly significant difference compared with no bisphosphonates in distant recurrence (18.4% vs 21.9%, respectively; P = .0003) and in bone recurrence (5.9% and 8.8; P<.00001). Bisphosphonates did not significantly reduce distant recurrences other than in bone in postmenopausal women.
The rate of breast cancer mortality was 15.2% for postmenopausal women treated with bisphosphonates compared with 18.3% not receiving bisphosphonates (P = .004), and the rate of all-cause mortality was 21.5% versus 23.8%, respectively (P = .007).
Reference
Coleman R, Gnant M, Paterson A, et al; Early Breast Cancer Clinical Trials Collaborative Group (EBCTCG)’s Bisphosphonate Working Group. Effects of bisphosphonate treatment on recurrence and cause-specific mortality in women with early breast cancer: a meta-analysis of individual patient data from randomized trials. Presented at: San Antonio Breast Cancer Symposium; December 12, 2013; San Antonio, TX. Abstract S4-07.