To stop or not to stop? International physician survey on HER2 targeted therapy for metastatic breast cancer patients in remission

Abstract

Introduction HER2-targeted therapy (HER2-TT) has improved outcomes in HER2+ metastatic breast cancer (MBC) with increasing numbers of long-term survivors in complete response (CR). Little is known about discontinuing maintenance HER2-TT in these patients. Methods An online survey of physicians was conducted via the Breast International Group (BIG) network between 30 October 2024 and 1 January 2025 to gather insights on HER2-TT use. Results A total of 237 physicians from 197 institutions in 38 countries answered the questionnaire. Most reported full access to trastuzumab (88.6%) and pertuzumab (80.6%). While 23.6% of physicians estimated that ≥30% of their HER2+ MBC patients diagnosed over the past decade are still alive >5 years post diagnosis, 86.1% reported that <25% of patients with no evidence of disease after treatment have discontinued HER2-TT. About 59.5% believed that HER2+ MBC can be cured, while 21.9% were unsure, and 18.6% believed that it cannot be cured. Less than half (43.9%) felt that maintenance HER2-TT could be stopped in patients in CR for prolonged period; 49.8% selected “maybe”. Opinions on timing of discontinuation after achieving CR were split: 21.1% favoured stopping after 1–<3 years, 25.3% after 3–<5 years and 40.5% after ≥5 years. Patient's choice was the most important factor in the decision making for discontinuing HER2-TT for 43.0% of physicians, followed by safety (31.6%) and physician's recommendation (15.2%). Conclusions Although majority of physicians believed that HER2+ MBC can be cured, most do not discontinue maintenance HER2-TT. Further data on outcomes after treatment cessation are needed to inform evidence-based optimization strategies.