To The Editor,

The author would like to congratulate Lee and their colleagues [1] in which the authors assessed the effects of adjuvant tamoxifen therapy on bone mineral density (BMD) changes in premenopausal women with primary breast cancer by conducting a meta-analysis of data from a systematic review. Their meta-analysis demonstrated that adjuvant tamoxifen therapy in premenopausal patients caused bone loss after 3 years of follow-up, especially at the lumbar spines. As authors stated that tamoxifen has anti-estrogenic effects on breast tissue but appears to be estrogenic on other tissues such as the uterus, bone, and vasculature. It would be expected that tamoxifen itself causes no harm to bone. Nevertheless, some premenopausal breast cancer patients experienced chemotherapy, which may have caused menopause at the time tamoxifen was started, or they received ovarian suppression (OVS) in addition to tamoxifen, which resulted in low estrogen levels once more and bone loss. Therefore, except for patients receiving chemotherapy beginning with menopause or tamoxifen with OVS, the negative effects of tamoxifen treatment on bone mineral density in premenopausal patients with breast cancer cannot be generalized to all patients. Further research is necessary on this matter.