By identifying the tumor-specific I TP53 i mutation through NGS tumor profiling of our patient's biopsy specimen, we were able to create a patient-specific ddPCR assay to follow this known driver of UESL. Despite the numerous worrisome lesions, interrogation of longitudinal plasma-derived cfDNA samples for the tumor-specific I TP53 i deletion has remained negative, supporting that these lesions were not indicative of sarcoma recurrence now more than 18 months off therapy (Fig 2). [Extracted from the article]