Abstract Approximately 70,000 adolescents and young adults are diagnosed with cancer between the ages of 15-39 in the U.S. every year. Due to their age and life stage, the experience of a cancer diagnosis as a young adult (YA) can lead to a cascade of emotional and physical challenges. A key obstacle faced by YA cancer patients is impaired social health, a complex construct that includes perceived social belonging, social support, and social network composition. YA patients report social health challenges such as maintaining existing and forming new social relationships after diagnosis, which may contribute to poor quality of life post-cancer. Diminished social health is a major risk factor for poorer health in the general population and has been found to reduce health-promoting behaviors such as physical activity, in part because of the lack of healthy opportunities and support that social contacts can provide. Cancer patients clearly benefit from greater levels of physical activity and lower levels of sedentary time as these are associated with improved quality of life, longer periods of disease-free survival, and lower mortality. Thus, understanding the relationships between social health, physical activity, and quality of life is critically important for YA cancer patients, as the impaired social health experienced by these patients may reduce their activity levels and endanger long-term health outcomes. The overall hypothesis is that social health in YA is negatively impacted following a cancer diagnosis, and that detriments in social health influence subsequent physical activity behaviors and survivorship quality of life (emotional well-being and physical function). In the proposed study, we will comprehensively prospectively assess social health over 12 months and examine its influence on activity behaviors and quality of life. Assessment will begin proximal to diagnosis when changes in social health are likely to initiate for YA cancer patients, with subsequent follow-ups at 3, 6, and 12 months. This longitudinal design will enable the examination of the dynamic changes in social health during and after therapy and its predictive influence on physical activity and quality of life. The Specific Aims are: Aim 1: we will characterize the trajectories of social health in YA cancer patients and assess their influences on quality of life in survivorship; Aim 2: we will investigate the longitudinal associations between social health and activity behaviors in YA cancer patients and test the mediational and reciprocal relationships between social health, activity behaviors, and quality of life; Aim 3: we will explore demographic and clinical moderators of the relationships between social health, activity behaviors, and quality of life. Understanding the mechanistic processes by which social health impacts activity behaviors and quality of life will inform the development of effective intervention strategies to foster social health and improve healthy survivorship for this at-risk and vulnerable population.

Narrative Social challenges are a major issue for young adult cancer patients (18-39 years old). Impairments in social relationships, referred to as social health, may decrease physical activity after a cancer diagnosis, leading to poorer quality of life after treatment and recovery. This study will investigate the relationships between social health, physical activity, and quality of life to expand our understanding of their interrelations to inform intervention strategies to foster healthy survivorship for young adult cancer patients.