243 Background: Much of the literature describing psychosocial consequences of cancer among adolescents and young adults (AYAs) has reported negative outcomes; however, AYAs also have potential for protective, positive outcomes. We aimed to prospectively characterize AYA patient-reported benefit and burden-finding after cancer diagnosis and hypothesized that benefit finding would be a salient coping mechanism. Methods: Semi-structured, 1:1 interviews were conducted with AYA patients after cancer diagnosis at 3 time points over 2 years, to elicit their expectations, hopes, worries, personal strengths, and challenges. A priori coding themes were defined from validated scales: changed sense of self, relationships, philosophy of life, and physical well-being. Verbatim transcripts were coded using content analyses by 3 independent coders for instances of benefit or burden by construct. Raw counts, ratios, and confidence intervals were calculated and compared by patient and time point. Results: Seventeen patients (mean age 17.1 ± 2.7; 8 [47%] male) completed 44 interviews with > 100 hours of transcript-data. Most common diagnoses were sarcoma (n = 8), acute leukemia (n = 6), and lymphoma (n = 3). Twelve patients completed all 3 interviews; reasons for withdrawal included death in all but 2 cases. Mean (±SD) counts of patient-reported benefit were higher than burden at each time point (T1, T2, T3); the benefit: burden ratio was > 1 in 68% of interviews (Table). Of the themes, changed sense of self was the most common benefit identified (44% of all reported benefits [95% CI 37%, 52%]) whereas physical complaints was the most common burden (32% [95% CI 25%, 39%]). Longitudinal analysis of subthemes among patients completing 3 interviews (N = 12) indicated an increase in self-identified positive and negative impact of cancer on personal, social and existential perspectives. Conclusions: AYA patients with cancer identified more benefits than burdens related to their diagnoses at all times studied. There was a shift over time in the distribution of benefit and burden finding constructs which may highlight areas for potential intervention. [Table: see text]