Patient Navigation for Improving Transition Success Among Multiply Disadvantaged Young Adult Survivors of Childhood Cancer - In recent years, aggregate 5-year survival after childhood cancer surpassed 85% and at least 500,000 individuals living in the US are childhood cancer survivors (CCS). Unfortunately, treatment-related late effects occur in more than two thirds of CCS and in half are severe or life-threatening, with a steadily rising cumulative incidence that results in premature mortality, excess morbidity, psychosocial distress, and lower quality of life. Given this life-long burden, formal transition of survivorship care from pediatric to adult-focused providers is recommended for CCS to ensure continuation of medically and developmentally appropriate management over the life span. Despite this, use of various transitional care models, knowledge of key transition barriers and facilitators, and the availability of published guidelines for late effects screening into adulthood have largely failed to achieve successful transition and optimal survivorship care for most young adult CCS. These issues are exacerbated among CCS who are low SES and are under/uninsured. Furthermore, emerging evidence shows that CCS report high unmet health-related social needs (HRSN) such as financial hardship, food insecurity, lack of transportation, low health insurance literacy, and psychological burden. Such survivors represent a population at even higher risk of early follow-up attrition, lower retention in guideline-concordant care, and downstream adverse impacts on health status. Patient navigation is an intervention that has robust evidence in adult cancer prevention and treatment but has not been studied for improving survivorship transition among CCS. The overall hypothesis is that a HRSN-informed patient navigator (PN) transition intervention will be effective in improving rates of successful transition for CCS. In this proposed study conducted at a safety net children’s hospital serving a high volume of CCS, we will use a PN to engage CCS dynamically beginning at transition and at 6, 12, and 18 months post-transition, with a focus on addressing HRSN to reduce transition barriers and enhance communication with the adult provider. An effectiveness-implementation hybrid design will be used to evaluate the implementation and value of this care model. The Specific Aims are: Aim 1: To evaluate, in a randomized controlled trial involving N=190 young adult CCS, the efficacy of a PN transition intervention for improving rates of successful transition. Aim 2: To identify moderators of the intervention. Aim 3: To measure the implementation, effectiveness, and value of the intervention through the RE-AIM (Reach, Effectiveness, Adoption, Implementation, and Maintenance) framework using quantitative and qualitative methods including in-depth interviews with CCS and clinical stakeholders. Testing a HRSN-informed PN intervention in this fashion will identify its potential value for improving transition success in CCS with a care model that is scalable, sustainable, and translatable to similar resource-constrained settings.