Bone Targeted Therapies in Early Breast Cancer

Adherence to bone health guidelines in patients with hormone receptor-positive early breast cancer: Status and clinical impact in a Swiss cohort experience

Aim

In patients with postmenopausal hormone receptor-positive breast cancer (ER + eBC), aromatase inhibitors (AIs) are widely used for effective relapse prevention. However, AIs reduce bone density and increase bone-related events (BREs). Alongside calcium and vitamin D3 supplementation, bisphosphonates and denosumab are well-known options for improving outcomes in bone health and breast cancer prognosis. This study aimed to evaluate the practice patterns of bone health guideline-based management in real-world patients with ER + eBC.

Material and methods

In total, 68 patients with ER + eBC treated between 2009 and 2014 at the University Hospital Basel were included in this retrospective cohort study. Chart reviews were analyzed. Baseline, clinicopathological, treatment, and BRE data were extracted. Each patient was specifically reviewed for therapy adherence to the Swiss bone health guidelines (Swiss Association against Osteoporosis 2010 [SVGO]).

Results

The mean patient age was 66.5 (range, 56–74) years, all post-menopausal. The most frequent tumor characteristics were tumor size of pT1–pT2 (N = 53, 77.9%) and treatment with letrozole (N = 35, 51.5%), followed by tamoxifen as a switch strategy (N = 27, 40.3%). The median treatment time with AIs was 47 (range, 30–60) months. Five patients (7.8%) experienced a fracture during or after AI treatment. Moreover, 51 (75%) patients were treated according to the SVGO recommendations.

Conclusion

The fracture rate in our retrospective cohort was comparable to that in the larger phase III randomized trials. The adherence to bone health guidelines was satisfactory but still suboptimal. Clinicians should strictly adhere to the current bone health guidelines to ensure the best possible prevention of BREs and maintain bone health and cancer prognosis in patients with ER + eBC.

Decreased risk of breast cancer associated with oral bisphosphonate therapy

Preclinical studies and adjuvant trials using bisphosphonates have found them to have an antitumor effect. Although major advances have been made in chemoprevention strategies with selective estrogen receptor modulators and aromatase inhibitors, their use has been fraught with significant adverse effects such as venous thromboembolic events and an increased risk for endometrial cancer. In this context, several recent observational studies have investigated a chemoprevention role for oral bisphosphonates in decreasing risk for breast cancer. This review will aim to summarize these studies and present a critical evaluation of the association between oral bisphosphonate use and breast cancer risk reduction.