Background: Individuals with cancer often endure a substantial physical and psychological symptom burden. However, little is known about the baseline symptom burden of patients with cancer participating in EP-CTs or the associations of this symptom burden with other PROs and clinical outcomes. Methods: We prospectively enrolled adults with cancer participating in EP-CTs at Massachusetts General Hospital from 4/2021-1/2023. Participants completed baseline surveys prior to EP-CT initiation that assessed symptoms (Edmonton Symptom Assessment System [ESAS]), quality of life (QOL; Functional Assessment of Cancer Therapy-General), hope (Herth Hope Index), depression/anxiety symptoms (Patient Health Questionnaire-4 [PHQ-4]), and financial wellbeing (COST tool, higher scores indicate greater financial wellbeing). We used regression models to explore associations of baseline symptom burden with other PROs (QOL, hope, depression/anxiety, financial wellbeing) and clinical outcomes (time on trial, hospitalizations, overall survival). Results: Among 205 participants (median age=63.3 [range: 31.8-88.6], 57.1% female), the most common cancer types were gastrointestinal (34.6%), breast (20.0%), and head and neck (10.2%). Based on the ESAS, approximately half of participants reported moderate/severe fatigue (50.2%) and poor wellbeing (49.5%). Under half reported moderate/severe drowsiness (35.7%), pain (25.9%), lack of appetite (25.4%), shortness of breath (20.0%), anxiety (18.0%), depression (15.4%), and nausea (9.2%). Higher baseline ESAS total, physical, and psychological scores were associated with worse QOL, lower hope, greater PHQ-4 depression/anxiety symptoms, and worse financial wellbeing (see Table). Higher baseline ESAS scores were associated with decreased time on trial and worse overall survival (see Table). Conclusions: In this study of EP-CT participants, we found associations of baseline symptom burden with other important PROs and clinical outcomes. Specifically, higher baseline symptom burden was associated with decreased QOL, lower hope, increased depression/anxiety symptoms, and diminished financial wellbeing as well as greater risk for shorter time on trial and worse survival. Interventions seeking to enhance care delivery and outcomes for EP-CT participants should strive to address the symptom burden of this population.