Circulating Tumor DNA Shows Potential as Biomarker in Rare Childhood Cancer

Analyzing circulating tumor DNA (ctDNA) in children with rhabdomyosarcoma, a rare adolescent soft tissue sarcoma, could help guide treatment, according to a study in this week's Journal of Clinical Oncology. Rhabdomyosarcoma is subdivided into two genetic subtypes, called fusion-positive and fusion-negative, and about half of patients are diagnosed with intermediate-risk disease. Because survival after relapse is unusual, it is important to identify patients who could be treated with standard therapy and those who should enroll in clinical trials for high-risk disease. Aiming to identify new biomarkers that could help do so, a team led by scientists from the Dana-Farber Cancer Institute applied two next-generation sequencing approaches to serum samples collected from 124 intermediate-risk rhabdomyosarcoma patients with either fusion-positive or fusion-negative disease. They find that ctDNA detection in these patients is significantly associated with a shorter event-free and overall survival, which could help refine prognoses in these patients. They also found that ctDNA was independently associated with outcome in patients with fusion-negative rhabdomyosarcoma. The findings, the study's authors write, "strongly suggest that ctDNA will be an important tool for future prognostication and risk-stratified treatment strategies" in rhabdomyosarcoma, although future studies in larger patient populations are needed.