Background: Significant changes were made in healthcare treatment (tx), safety standards, and protocols during the COVID-19 pandemic. mBC pts are particularly vulnerable to such changes, making it critical to understand their perspectives during this time. The REACT survey assessed US pt perspectives on the effect of COVID-19 on their mBC tx experience, leveraging technology from the MBC Alliance pt advocacy group to capture learnings and improve pt care. Methods: Pts ≥18 years old with mBC during the pandemic voluntarily completed a cross-sectional web-based survey using the MBC Connect pt registry portal between April 27–August 12, 2021. We describe initial results focusing on baseline pt demographics, health and mBC history, online services used, and perceived effects of COVID-19 on mBC care. Results: 341 mBC pts completed the survey (99% female; median age at time of survey, 50 [range, 29–78] years). 52% of pts were HR+/HER2–, 7% triple negative, and 36% HER2+ (5% other). 39% of all pts were de novo stage IV; 48% reported their disease progressed during the pandemic. 29% and 44% of all pts used online services to schedule COVID-19 tests and vaccinations, respectively. 81% (275) of pts used telemedicine; of these, 46% experienced difficulty using telemedicine (39% a little bit; 4% somewhat; 1% quite a bit; 1% very much). Among 178 pts with clinical visit changes due to COVID-19, most had changes in regular clinical checkups (88%) and mental health services (41%) (Figure). Among 84 pts with tx changes due to COVID-19, 54% had changes with chemotherapy and 48% with targeted therapy (38% and 36% of the 84 pts having doses delayed, respectively); pt perception of tx changes were a little worse in 40% and 33%, respectively. 13% of all pts had consultations with providers in other states, 9% had long-distance consultations in the same state, and 3% participated in clinical trials in other states or long-distance in the same state. Conclusions: Survey responders indicated the COVID-19 pandemic resulted in several changes to mBC care. Most pts used telemedicine and many had changes to scheduled clinical visits (ie, use of telemedicine, delays, cancellations). Most pts did not perceive changes as negative, and further elucidation of clinical impact is needed. Some pts utilized and may have benefited from inter-state care options. Understanding the pt perspective on changes that occurred in their mBC care can help improve care beyond the duration of the pandemic.