Endocrine Abstracts

Patients with endocrine-related cancers are notably at increased risk for developing osteoporosis as a complication from their adjuvant anticancer treatment, especially aromatase inhibitors (AIs) in early breast cancer (EBC) and androgen deprivation therapy (ADT) in early prostate cancer (EPC). AI-induced bone loss (AIIBL) occurs at a rate at least 2-fold higher than bone loss seen in healthy, age-matched postmenopausal women and they have a more than 30% higher risk of fractures. Recently considered fracture risk factors in EBC are AI therapy, T-score <−1.5, age >65 years, family history of hip fracture, history of fragility fracture after age 50, oral corticosteroid use >6mo, smoking, and BMI <20 kg/m². The WHO-FRAX algorithm does not address AIIBL and may underestimate EBC fracture risk. General advice includes exercise, calcium/vitamin D supplements, and baseline BMD monitoring. Bisphosphonates and denosumab can preserve BMD during AI therapy for EBC. Poor compliance may reduce oral bisphosphonate benefits. Overall, bisphosphonate evidence is strongest for zoledronic acid (ZOL; 4 mg q6mo). Potential anticancer activity of ZOL might provide benefits beyond preserving bone mass. Patients initiating AI with T-score <−2.0 or ≥2 risk factors should receive appropriate antiresorptive therapy. Bone loss that occurs with ADT is also more rapid and severe than that associated with normal age-related bone loss. ADT also increases fracture risk and the hazard ratios appear to be comparable to the ones reported for AIs in breast cancer. There are a few randomized studies in patients with prostate cancer demonstrating that bisphosphonates, notably ZOL, can prevent bone loss under ADT. The effects of denosumab (60 mg sc q6mo) on bone loss and incidental vertebral fractures have been demonstrated in a large-scale placebo-controlled trial in the setting of ADT-induced bone loss. Specific guidelines are lacking for the treatment and the prevention of ADT-induced bone loss.

Declaration of interest: The author declares that there is a conflict of interest.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.