Clinical practice patterns on the use of adjuvant bisphosphonate for early breast cancer: A Canadian perspective.

Abstract

e12002 Background: Adjuvant bisphosphonates (ABPs) in menopausal women with early breast cancer (EBC) decrease the risk of BC relapse and modestly improve overall survival (OS). In the era of personalized medicine, a one size fits all approach is not ideal–it is important to identify the subgroup of patients who may not derive a clinically meaningful benefit to avoid over treatment, unnecessary toxicity, and optimize resource utilization. Objectives: To better characterize how Canadian medical oncologists (MOs) use ABPs and whether practice patterns are concordant with the CCO/ASCO guideline. Methods: A brief survey was circulated by e-mail to 618 Canadian MOs between Nov 2017 - May 2018. Questions were designed to gather data on demographics, patient selection, choice of bisphosphonate, schedule/duration of treatment and barriers to use. No incentive was provided. Results: Sixty-eight MOs from 8 Canadian provinces completed the survey (response rate 11.0%). Most practiced in Ontario (65.7%) and just over half (51.5%) were community oncologists. MOs offered ABPs to 52.2% of menopausal women with EBC. Use was higher in the community compared to the academic setting (p=0.049). Most used zoledronic acid (85.3%) every 6 months (95.6%) for 3 years (69.1%) and started treatment within 3 months of completing adjuvant chemotherapy/radiation (67.7%). Factors associated with use of ABPs were: high Oncotype Dx score (89.1%), high tumor grade (72.1%), triple negative disease (63.6%), osteoporosis (87.7%)/osteopenia (83.9%) and use of aromatase Inhibitor (75.0%). The most common factor precluding use of ABPs was presence of comorbidities (89.7%). About 1/3rd indicated they would offer ABPs to women with stage I HR positive/Her2 negative EBC. Conclusions: Canadian MOs have added intravenous ABPs to their armamentarium of therapies in keeping with the spirit of the recent guideline. High-risk disease features and low bone density appear to be influencing the decision-making process. Further work aimed at identifying those patients who are unlikely to benefit from treatment is needed.