Background: It is well known that adjuvant tamoxifen treatment for breast cancer in postmenopausal women decreases bone loss. However, the adverse effect of adjuvant tamoxifen therapy for bone mineral density (BMD) in premenopausal breast cancer patients remains uncertain. This meta-analysis aimed to assess the effects of adjuvant tamoxifen therapy on BMD changes in premenopausal women with primary breast cancer. Methods: Through April 2020, studies reporting BMD changes of lumbar spine or hip in premenopausal women with primary breast cancer treated with adjuvant tamoxifen were collected from EMBASE and PubMed. The pooled analysis was performed using random effects model of the standardized mean difference (SMD) of BMD in patients. Results: A total of 1,432 premenopausal patients from eight studies were included in the pooled analysis. After 3 years of median follow up, adjuvant tamoxifen therapy decreased BMD by as much as SMD of -0.79 [95% confidence interval (CI); -1.25 to -0.33, P< 0.01] at lumbar spines and -0.38 at hip (95%CI; -0.88 to 0.12, P > 0.05). Compared with patients received tamoxifen alone, patients who received combination therapy with chemotherapy or ovarian function suppression (OFS) showed decreased bone loss at lumbar spine (SMD -1.17 with 95%CI -1.59 to -0.75, -0.43 with 95%CI -2.26 to 1.40, and -0.75 with 95%CI -1.38 to -0.13, respectively). Conclusions: Our meta-analysis revealed that premenopausal women who received adjuvant tamoxifen treatment showed significant bone loss over a period of time, especially at lumbar spine. However, tamoxifen attenuated bone loss in those who received tamoxifen after chemotherapy or along with OFS.

No., number; BMD, bone mineral density; L, lumbar; CTx chemotherapy.