Background: 
Implementation science for cancer control aims to accelerate and improve the widespread adoption and use of cancer control evidenced-based interventions (EBIs) to ensure all populations worldwide benefit from lifesaving interventions. However, successful implementation hinges on a deep understanding of context. Public health research communities and health systems must have the capacity to systematically adapt evidence to their contexts and, in doing so, generate insights that contribute back to the field. To support this, the LISTOS for Cancer Control Center was launched in 2023 through a U.S. National Cancer Institute initiative to improve the adoption, integration, and sustainment of evidence-based cancer control interventions (EBIs) in Mexico and Latin America and contribute to advancing the science of implementation in low-and-middle income countries (LMICs). 

Objectives: 
1) Increase the reach, effectiveness, and sustainment of cancer control interventions in health care systems that serve disadvantaged populations in Mexico, through adaptation of evidence-based cancer-control interventions, and the design and tailoring of innovative and scalable implementation strategies. 2) Build implementation research capacity in Mexico and Latin America through innovative approaches to training and mentoring. 3) Cultivate partnerships with decision-makers in Mexico’s centralized public health systems to support long-term impact and policy uptake. 

Methods: 
The LISTOS Center currently supports three implementation studies (two trials and one pilot study) addressing three pressing cancer control priorities in Mexico: colorectal cancer screening, early breast cancer diagnosis, and HPV-based cervical cancer screening. Community and stakeholder engagement and co-creation with health system leaders and stakeholders increase buy-in and build institutional readiness for implementation science approaches. Each study is embedded within a different publicly funded health system and led by Mexican investigators (mentees). Mentees conduct their studies with support from a Center-wide ecosystem of consultants, experienced implementation scientists, methodologists, and training resources, including tailored mentoring plans, protocol co-development, and analytic coaching. All studies are guided by a shared conceptual model that integrates multiple frameworks. To guide the adaptation and implementation strategy design processes needed to optimize cancer control evidence-based interventions we are using IM Adapt and Implementation Mapping. To inform our needs assessments, we are using the Consolidated Framework for Implementation Research (CFIR) and the Interactive Systems Framework (ISF). To define outcomes of implementation we are using the Reach Effectiveness Adoption Implementation Maintenance (RE-AIM) framework.  

Results: 
All three studies have completed initial needs assessments to inform the contextual adaptation of evidence-based interventions and the design of implementation strategies appropriate to each health system and cancer control challenge.  Partnerships with health system leaders have facilitated alignment with institutional priorities and co-design for enhanced fit and sustainability.  

Conclusions/Implications: 
LISTOS demonstrates a dual-impact model for advancing cancer control in LMICs: strengthening research capacity in Mexico while building strategic partnerships that increase institutional buy-in and readiness for implementation.