Effect of Vitamin D on Bone Mineral Density Changes in Patients with Breast Cancer Receiving Adjuvant Aromatase Inhibitor Therapy

Park, Sang Hoon; Kim, Eun Young; Park, Chan Heun

Abstract

PURPOSE
We assessed bone mineral density (BMD) changes with aromatase inhibitor (AI) treatment in women with breast cancer and determined whether BMD T-scores changed with vitamin D supplementation.
METHODS
This single-center, retrospective study included postmenopausal patients with breast cancer who had undergone surgical resection of stage I, II, or III estrogen- and/or progesterone-receptor-positive breast cancer and received adjuvant AIs (letrozole, anastrozole, and exemestane) at Kangbuk Samsung Hospital from January 2003 to July 2017. Baseline BMD T-scores of the femoral neck, proximal femur, and lumbar spine were obtained. The first group received vitamin D oral supplements (25,000 IU, monthly) or intravenous (IV) injections (200,000 IU, every 6 months). The second group did not receive vitamin D. T-scores were re-assessed at 12 and 24 months. BMD changes in the femoral neck, proximal femur, and lumbar spine were examined and compared according to vitamin D therapy.
RESULTS
A total of 118 women were included in the study. Eighty-four patients (71.2%) were aged >50 years, and most patients (64.1%) were postmenopausal. Group 1 (n=76, 64.4%) had received vitamin D oral supplements (25,000 IU, monthly) or IV injection (200,000 IU, every 6 months) during AI therapy. Group 2 (n=42, 35.6%) did not receive vitamin D during AI therapy. At baseline, 42.2% and 28.6% exhibited osteopenia at the femoral neck in Group 1 and Group 2, respectively. Both groups had T-score declines after AI therapy, with mean decreases of 0.23 and 0.41 at the femoral neck and lumbar spine, respectively, after 12 months and 0.40 and 0.55 at the femoral neck and lumbar spine, respectively, after 24 months in Group 1. However, differences in BMD T-score change at the femoral neck, total proximal femur, and lumbar spine between the groups were not statistically significant.
CONCLUSION
Trends toward a decline in BMD in the femur and lumbar spine were observed in postmenopausal women with breast cancer receiving AI therapy. We did not observe a protective role of vitamin D supplementation against bone loss with AI therapy. A longer follow-up duration is necessary to determine whether vitamin D protects against bone loss during AI therapy.