Bisphosphonate use for the management of breast cancer patients with bone metastases: A survey of Canadian Medical Oncologists

Background: The use of bisphosphonates (BP) in breast cancer patients with bone metastases (BM) has been shown to reduce bone pain and lower the risk of skeletal-related events (SREs). Many practice guidelines exist for the use of BPs in patients with BM. Unfortunately, none clearly address whether the benefits of BP use apply equally to all subgroups of patients, the duration of therapy, and when to discontinue BP therapy. A questionnaire was therefore developed and administered to determine how medical oncologists in Canada use BPs in clinical practice. Methods: A structured mailing strategy was adopted. The population consisted of 100 medical oncologists with active breast cancer practices in Canada. All regions of Canada were represented. The questionnaire was developed to capture data on respondent demographics, BPs used, major factors influencing decision making, and clinical practice in situations where there is a lack of high-quality data. Results: Completed questionnaires were returned by 76 medical oncologists. All treated breast cancer and the majority (68%) were based at teaching hospitals. Ninety-six percent of respondents regularly prescribed BPs, initiating therapy at the time the patient presented with BM. Although 79% of respondents recognized that there was no clear data to support the continued use of BP after bony progression, 53% stated that they rarely or never discontinue a BP once started. In situations where a BP was discontinued, the majority of respondents report the reason for discontinuation was a decrease in patient performance status. In the patient with clearly progressive visceral metastases and an estimated prognosis of less than 6 months, 75% of respondents would still commence BP therapy. Conclusions: This study confirms that most medical oncologists in Canada, while acknowledging lack of evidence, maintain patients on BP therapy when patients have an expected survival of less than 6 months or even after patients progress while on a BP. More research is needed to determine the role of continuing, switching, or discontinuing BP therapy in the context of disease progression or shortened expected survival.