Osteoporosis after adjuvant treatment for early-stage breast cancer

Introduction: Adjuvant treatment of early-stage breast cancer has been associated with bone loss in randomised trials, but evidence from unselected populations is needed. In a single-center study, we assessed the annual percentage change in bone mineral density (&BMDt) and risk of osteoporosis from two to five years after adjuvant chemotherapy in patients with oestrogen-receptor-positive and oestrogen-receptor-negative tumours. Methods: Dual energy X-ray absorptiometry (DXA) was performed in 241 recurrence-free Danish breast cancer patients, among whom 157 had a prior DXA scan within two years of chemotherapy (“early”). Linear regression was used to assess &BMDt in spine and hip according to age, different health-related variables and time since early DXA. Results: Based on 157 patients, we observed annual decreases in spine BMD of 1.73%      (95% confidence interval (CI): –2.01-– 1.44, p < 0.001) and hip BMD of 1.30% (95% CI: –1.51-–1.09, p < 0.001). Patients aged less than 50 years at diagnosis had a significant decrease in mean spine BMD of 2.23% (95% CI: –2.78-–1.68), whereas the decline was more limited in patients aged 50-59 years and patients aged 60 years or older with a mean spine BMD of 1.70% (95% CI: –2.07-–1.34) and 0.81% (95% CI: – 1.42-–0.20), respectively. The results persisted in multivariable analyses. Osteoporosis was diagnosed in 9% of patients, all postmenopausal. Conclusions: Adjuvant anthracycline-taxane-based chemotherapy followed by endocrine therapy caused bone loss, especially in younger compared with older patients with early-stage breast cancer, confirming the results from randomised trials.