Clinical Characteristics, Treatment Considerations, and Outcomes of Infants with Rhabdomyosarcoma

Simple Summary Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma among infants. The clinical characteristics and biology of RMS among infants are distinct from those of older children with RMS. The management of infants with RMS follows a parallel approach of risk-stratification and treatment with multimodality chemotherapy in combination with surgery and/or radiation. but with a few caveats. Modification of chemotherapy regimens is often needed to reduce the risk of excessive treatment-related morbidity due to developmentally immature organs. Adequate surgical resection is more challenging due to the technical difficulties associated with large tumors arising from critical structures in small-sized patients. Similarly, irradiating developing organs can impair long-term function or form and increase the risk of secondary malignant neoplasms. A few clinical trials conducted by international cooperative groups have addressed the challenges of managing infants with RMS and their outcomes. RMS most commonly presents in children and adolescents, however a subset of tumors are diagnosed in infants under one year of age. Due to the rarity of infant RMS, utilization of different treatment approaches and goals, and small sample sizes, the published studies of infants with RMS have yielded heterogeneous results. In this review, we discuss the outcomes of infants with RMS treated in various clinical trials and the strategies that various international cooperative groups have employed to reduce the morbidity and mortality related to treatment without compromising the overall survival of this population. This review discusses the unique scenarios of diagnosing and managing congenitals or neonatal RMS, spindle cell RMS and relapsed RMS. This review concludes by exploring novel approaches to diagnosis and management of infants with RMS that are currently being studied by various international cooperative groups.