11010 Background: Patient, provider, and system-level barriers contribute to significant disparities in care of LGBTQ+ persons, including delays in screening and diagnosis, and poorer outcomes. This implementation science initiative was designed to identify and address root causes of disparities in care for LGBTQ+ patients (pts) and drive sustainable change to improve health equity in LGBTQ+ cancer care. Methods: In 2023, a steering committee of 3 expert oncologists and 5 LGBTQ+ cancer pts convened to develop survey instruments and a point-of-care LGBTQ+ Cancer Care Toolkit. Next, LGBTQ+ pts with cancer (N = 817) and oncology providers (OPs) from 2 academic and 5 community-based practices (N = 115) completed surveys to reveal alignments and discordances in beliefs, perceptions, and practices regarding cancer care. OPs participated in audit-feedback (AF) sessions to critically assess system-specific practice gaps, prioritize areas for improvement, and develop action plans for improving LGBTQ+ cancer care. Results: Provider-reported top challenges in care included: unsure how sexual orientation/gender identity (SOGI) affect treatment considerations (35%), unsure how to discuss SOGI (30%),and systemic barriers that limit inclusion (29%). While most providers (84%) were at least moderately comfortable treating LGBTQ+ pts, these data suggest they overestimated the level of comfort of their pts. For example, only 24% of pts reported feeling safe disclosing their LGBTQ+ identity, while 65% of providers thought pts felt safe. Additionally, while most providers (73%) thought it was important to know a pt’s gender identity, only 46% thought it was important to know sexual orientation, and only 3% of providers reported routinely discussing SOGI with new pts. Patients and providers were not concordant in several other key areas, including the experience of pts’ partners, measures of inclusivity, and supportive care services offered, such as fertility preservation. Survey data also revealed systemic barriers to equitable care, such as EMR documentation of SOGI. In AF sessions, teams reviewed survey outcomes, and developed action plans for improvement, including integrating the toolkit, updating EMR documentation, developing LGBTQ+ education, and adopting measures of inclusivity. Notably, following the intervention, there were considerable gains in provider confidence and knowledge, and ~70% of providers committed to discussing SOGI with their pts at first introduction. Conclusions: Through this QI initiative, teams identified patient-, provider-, and systemic-level barriers that affect LGBTQ+ cancer care in their own practices and implemented action plans to address key challenges. The sustainable changes implemented in this QI initiative represent key opportunities for improvement that can be implemented in clinics across the country to improve equitable LGBTQ+ cancer care.