Background: Antiresorptive therapy is a cornerstone in the management of patients with metastatic breast cancer with bony metastases. We aimed to evaluate current clinical antiresorptive prescribing practices of medical oncologists in Australia and New Zealand.
Methods: Members of the Australian and New Zealand breast cancer trials group were invited to complete a questionnaire survey online or on paper. Questions included the types of antiresorptive agents used, dosing, frequency, duration and monitoring of side effects.
Results: Our response rate was 37.8% (91/241). Respondents had been working in medical oncology for a median of 15 years (range 4-40). Most (81%) prescribed an antiresorptive agent in all patients with bony metastases with 83% of respondents using denosumab as their standard treatment for newly diagnosed bone metastases. Co- prescribing of oral calcium and vitamin D was seen more with the use of denosumab than bisphosphonates. (Always: 64% vs 20%). Dental review was advised by most (69%) before commencement. Dosing frequency was similar for IV bisphosphonates and denosumab with many decreasing frequency of administration of both agents over time (93.3% and 58.7% respectively). Renal function was a more important factor in IV bisphosphonate use. 56% of clinicians did not consider a maximum duration of therapy. 24% stopped antiresorptive therapy (median 30 months, range 24- 60 months). Osteonecrosis of the jaw was uncommon (one case every 2-5 years – 29.2%, less than one case per 5 years – 23.6%) as were atypical fractures. Most (97%) withheld treatment for dental extraction with some (42%) using prophylactic antibiotic cover and more (56%) recommencing when healed rather than a fixed period from extraction.
Conclusions: The varying use of antiresorptive agents seen in this survey highlights the need for further research to optimize the use of these agents in a group of patients whose life expectancy has increased considerably over the past decades.