BACKGROUNDAdolescents and young people (AYA) with cancer are at greater risk of psychological distress which can impact treatment. COVID-19 has resulted in changes to cancer care delivery and AYA have been disproportionately affected by economic and educational effects of COVID-19, potentially impacting on mental health. Understanding the impact of COVID-19 on AYA with cancer is important to inform care.METHODSOnline survey of 16-24 year olds receiving cancer treatment at 8 cancer centres in the UK in December 2020. We measured: self-perceived increased anxiety since COVID-19, impact of COVID-19 on treatment, life and relationships and used the 8-item Patient Health Questionnaire(PHQ-8), 7-item Generalised Anxiety Disorder Scale(GAD) and the 2-item Connor-Davidson Resilience Scale(CD-RISC).RESULTS112 AYA participated (17.8% of total eligible). 62.8% were female, 67.3% were 21-24 years. 83% were white. 59.8% had previously experienced mental health difficulties. 67.9% received cancer treatment during the pandemic and 33.9% were diagnosed during the pandemic. 78.6% reported COVID-19 having a significant impact on their life, 55.4% on their key relationship and 39.3% on their treatment. 79% reported experiencing some degree of increased anxiety since COVID-19.43.4% had moderate-severe PHQ-8 scores and 37.1% for GADS-7. Self-report of impact on life was associated with greater anxiety during COVID-19 and moderate-severe PHQ-8 score (OR 3.64, 95% CI 2.52 to 19.40, p CONCLUSIONSWe found high levels of psychological distress in AYA with cancer, which is important knowledge for clinical teams working with this age group. Perceived impact of COVID-19 on relationships and life was predictive of poorer mental health, with resilience a potential protective factor.