Cytotoxic chemotherapy is associated with decreased bone mineral density in postmenopausal women with early and locally advanced breast cancer

PURPOSE: The burden and mechanisms of endocrine therapy-related bone loss have been studied in detail. However, there is limited data regarding cytotoxic chemotherapy’s impact on bone health. There are no definitive guidelines for bone mineral density (BMD) monitoring and treatment with bone-modifying agents during cytotoxic chemotherapy. The study’s primary objective was to evaluate the changes in BMD and fracture risk assessment tool (FRAX) scores among breast cancer women on cytotoxic chemotherapy. METHODS: One hundred and nine newly diagnosed early and locally advanced postmenopausal breast cancer patients planned for anthracycline and taxane-based chemotherapy were recruited prospectively during the study period from July 2018 to December 2021. BMD of the lumbar spine, the femoral neck, and the total hip were assessed by dual-energy X-ray absorptiometry scan. BMD and FRAX scores were evaluated at baseline, end of chemotherapy, and 6 months of follow-up. RESULTS: The median age of the study population was 53 (45–65) years. Early and locally advanced breast cancers were seen in 34 (31.2%) and 75 (68.8%) patients, respectively. The duration of follow-up between two BMD measurements was 6 months. The percentage of decrease in BMD at the lumbar spine, femoral neck, and total hip were − 2.36 ± 2.90, − 2.63 ± 3.79, and − 2.08 ± 2.80, respectively (P-value = 0.0001). The median risk of major osteoporotic fracture (MOF) at 10 years (FRAX score) increased from 1.7 (1.4) to 2.7% (2.4) (P-value = 0.0001). CONCLUSION: This prospective study in postmenopausal breast cancer women shows a significant association of cytotoxic chemotherapy with the worsening of bone health in terms of BMD and FRAX score. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11657-023-01231-z.