Importance of the field: Breast cancer is one of the leading causes of cancer-related deaths in the world. Despite the significant improvements in the adjuvant treatment strategies of early-stage breast cancer, many patients experience relapse. Bisphosphonates are widely used in the treatment of bone metastasis of solid tumors and multiple myeloma, as well as in osteoporosis. The results of clinical studies of adjuvant treatment on early-stage hormone-receptor-positive breast-cancer patients under hormonal treatment - especially with the bisphosphonate zoledronic acid - caused excitement because they demonstrated an additive effect on decreasing disease relapses at bone or other sites. A number of clinical and in vitro and in vivo preclinical studies, which are either ongoing or have just ended, are investigating the mechanisms and antitumoral activity of bisphosphonates.
Areas covered in this review: The current literature on the preclinical and clinical studies into antitumoral effect and adjuvant treatment of bisphosphonates, especially zoledronic acid, are summarized. Data in the literature over the last two decades were also reviewed.
What the reader will gain: The reader will find a summary of preclinical and clinical studies of antitumoral effect and adjuvant treatment with bisphosphonates, in particular zoledronic acid, as well as ongoing trials about adjuvant treatment of breast cancer with zoledronic acid and ibandronate.
Take home message: Current evidence supports zoledronic acid as an effective treatment in adjuvant breast-cancer therapy for hormone-receptor-positive breast-cancer patients when added to hormonotherapy. Uncertainty about effects of zoledronic acid and other bisphosphonates will be clarified after completion of ongoing trials.