Whole-genome sequencing to improve sarcoma diagnosis and patient care

11540 Background: With more than 70 different histological subtypes, accurate classification sarcomas is challenging. Although pathognomonic genetic events aid accurate classification, large-scale molecular profiling is generally not incorporated in regular diagnostic workflows for sarcoma patients. We hypothesized that whole genome sequencing (WGS) optimizes clinical care of sarcoma patients by detection of pathognomonic and actionable variants, and of underlying hereditary conditions. Methods: WGS of tumor and germline DNA was incorporated in the diagnostic work-up of 83 patients with a (presumed) sarcoma as part of the WIDE (Whole genome sequencing Implementation in standard Diagnostics for Every cancer patient) study in a tertiary referral center. WGS results were reported back to the pathologist and treating clinician. Clinical follow-up data were collected prospectively to assess impact of WGS on clinical decision making. Results: WGS analysis had impact on multiple levels. First, in 14% of cases (12/83 patients), the genomic profile led to a revision of the diagnosis (table). All patients had undergone multiple diagnostic procedures (mean number: 4) and pathologist assessments (mean: 6) before WGS analysis was performed. Secondly, actionable biomarkers with therapeutic potential were detected for 36/83 patients and finally, 8 pathogenic germline variants were present. Taken together, WGS had implications for clinical decision making in 52% of patients with (presumed) sarcomas. Conclusions: WGS is an important extension of the diagnostic arsenal of pathologists and has contributed to change of care in 52% of patients with sarcomas. Given the diagnostic complexity and high unmet need for new treatment opportunities in sarcomas we advocate the use of WGS for sarcoma patients early in the disease course. Clinical trial information: NL68609.031.18. [Table: see text]