Implementation of integrated care for rapid breast cancer diagnosis ABSTRACT Consistent with the second pillar of WHO's Global Breast Cancer Initiative for improving breast cancer (BC) control in LMICs, our long-term goal is to improve the timeliness of breast cancer diagnosis in Mexico. The goal of the proposed study is to develop and test implementation strategies designed to improve integrated care for rapid BC diagnosis across health system levels among women presenting with BC in primary care settings. The Specific Aims are: (1) Assess barriers, facilitators, and organizational readiness for implementation of rapid BC diagnosis system. We will conduct qualitative interviews with healthcare personnel (informed by CFIR and ISF frameworks) to identify barriers and facilitators for implementation. Also, we will cross culturally adapt the R=MC 2 measure and assess organizational readiness across the 166 primary care centers that serve the uninsured population in Monterrey, Nuevo León. (2) Develop strategies to improve the implementation of a rapid BC diagnosis system. Using Implementation Mapping in collaboration with the key stakeholders, we will design contextually appropriate implementation strategies (including practice facilitation) to address barriers and strengthen organizational readiness for implementation of integrated care that will enable rapid diagnosis. (3) Evaluate the impact of practice facilitation on implementation of a rapid BC diagnosis system and determine effectiveness on patient outcomes. We will conduct a hybrid type 2 implementation-effectiveness study using a cluster randomized stepped-wedge design. Primary implementation outcome: reduction in the time between symptomatic presentation at the primary care clinics and arrival to the diagnostic clinic. Effectiveness outcome: down-shift in the stage of BC. The proposed study will address a pressing need in BC control in Mexico (and other LMICs), and advance implementation science by adapting and validating a Spanish language organizational readiness measure and evaluating the use of practice facilitation to improve readiness for implementation of cancer control practice change in LMICs.