Effects of zoledronic acid versus placebo on bone mineral density and bone texture analysis assessed by the trabecular bone score in premenopausal women with breast cancer treatment-induced bone loss: results of the ProBONE II substudy

Changes in bone mineral density (BMD) and trabecular bone score (TBS) were assessed in 70 patients who received either zoledronate (ZOL) (n = 34) or placebo (n = 36) for 2 years. In premenopausal women with breast cancer treatment-induced bone loss, 24 months of intravenous ZOL treatment significantly increased the lumbar spine BMD and the TBS. The aim of this study was to compare the effects of 4 mg intravenous zoledronate (ZOL) versus placebo (PLB), every 3 months, on the lumbar spine (LS) bone mineral density (BMD) and the trabecular bone score (TBS) in premenopausal women with breast cancer (BC) treatment-induced bone loss. The TBS is a gray-level texture measurement which is related to the bone microarchitecture and considered to be independent of the BMD. Changes in BMD and TBS were assessed in 70 patients who were recruited in the double-blind, placebo-controlled ProBONE-II trial and randomized to receive either ZOL (n = 34) or PLB (n = 36) for 2 years. The changes were assessed at baseline and at 12 and 24 months after treatment initiation. Patients receiving ZOL showed a mean increase in LS BMD from the baseline to 12 (2.17 %) and 24 months (3.14 %) of treatment and a mean increase in the TBS of 2.41 and 0.75 %, respectively. Conversely, patients receiving PLB showed a mean decrease in the LS BMD from the baseline to 12 (-5.02 %) and 24 (-6.43 %) months and a mean decrease of -0.52 and -2.16 % in the TBS, respectively. Changes in the BMD and the TBS from the baseline to 12 and 24 months were all significantly different for ZOL compared to PLB (p < 0.005). Furthermore, BMD and TBS showed a moderate correlation ranging from 0.28 (p = 0.087) to 0.47 (p = 0.003). In premenopausal women with BC, 24 months of intravenous ZOL treatment significantly increased the LS BMD as well as the TBS.