Prevention of Osteoporosis in Patients With Breast Cancer Treated With Aromatase Inhibitor Combined With Calcium/Vitamin D Supplements

Purpose: Tamoxifen and aromatase inhibitor (AI) are used for hormone therapy for hormone-positive breast cancer, and AI is well known to decrease bone mineral density (BMD). The authors compared the serial BMD of patients with hormone-positive breast cancer to evaluate the preventive effect of AI combined with calcium and vitamin D (Ca/Vit D) supplements.Methods: A total of 249 women with hormone-positive breast cancer who underwent serial BMD assessments between 2011 and 2015 were included. The patients were classified as the tamoxifen alone group (n=23), AI with Ca/Vit D group (n=139), and extended regimen from tamoxifen to AI with Ca/Vit D group (n=87). Moreover, osteoporosis was diagnosed based on the World Health Organization guideline.Results: The incidence of osteoporosis was highest in the AI with Ca/Vit D group (n=50, 36.0%) and lowest in the tamoxifen only group (n=4, 17.4%). Furthermore, it showed statistical difference between the three groups (p=0.003). However, considering the baseline of initial BMD in each patient, the mean change value did not show any statistical difference between the three groups (p=0.498). Moreover, the lumbar T-scores were lower than that of the total hip T-scores in each patient.Conclusion: Although it has been reported that osteoporosis is common in patients treated with AI, the decreased BMD was not significantly severe compared to that in the tamoxifen alone group if Ca/Vit D was administrated with AI. Therefore, Ca/Vit D has some preventive effect for osteoporosis in patients treated with AI.