A Multicenter Physician Survey Evaluating the Use of Ki-67 in Breast Cancer Management in Canada.

Background: Ki-67's response to pre-operative endocrine therapy (ET) in early breast cancer is an evidence-based tool to guide adjuvant treatment decisions. Physicians across Canada were surveyed to explore current practice patterns and perceived barriers to the use of Ki-67 in practice.

Methods: Physicians were invited to participate in an anonymous survey and were eligible if they prescribed systemic therapy for breast cancer in Canada. Respondents were asked to describe their usage of Ki-67, perceptions of the evidence surrounding Ki-67 ET response, and interest in future trials using this approach.

Results: The survey received 48/163 responses (29.4%). The majority of respondents (97.6%) reported access to Ki-67 testing upon request. Treatment decisions for adjuvant Abemaciclib was the most common reason (97.6%), followed by adjuvant chemotherapy decisions (16.7%). Only 19.0% had used Ki-67's response to pre-operative ET in practice. Common barriers to this approach that were identified included a lack of awareness from other providers (54.8%), an increased resource requirement (54.8%), and a lack of timely medical oncology consultation (52.4%). The majority of physicians (85.3%) reported that they would participate in future trials using the Ki-67 endocrine response, and that rate of treatment decision change (95.2%) and cost analysis (42.3%) were important endpoints.

Conclusions: Despite the widespread availability of Ki-67 testing, few physicians in Canada currently use it to assess endocrine response, predominantly due to logistical and resource constraints. There is a high level of interest in participating in future trials using this strategy, which should focus on disease related outcomes, feasibility, and the financial impact on the public healthcare system.