Bone and Soft Tissue Neoplasms in Infants Versus Older Children: A Report From the Cancer in Young People in Canada...

Infant bone and soft tissue neoplasms present distinct clinical challenges and lack large-scale data to inform treatment decisions. This study aims to characterize bone and soft tissue neoplasms in infants in Canada and to compare their outcomes with those of older pediatric patients.

We conducted a retrospective population-based cohort study using the Cancer in Young People in Canada (CYP-C) database, including all children <10 years with extracranial bone and soft tissue neoplasms diagnosed between 2001 and 2020. Kaplan-Meier and Cox regression analyses compared treatment-related mortality (TRM), cumulative incidence of relapse (CIR), event-free survival (EFS), and overall survival (OS) between infants (<1 year) and older children (1 to ≤10 years).

A total of 1102 children with bone and soft tissue neoplasms were included, including 146 infants (13.2%). The most common infant tumor subtypes were fibrosarcoma (28.8%), malignant rhabdoid tumors (26.7%), rhabdomyosarcoma (25.3%), clear cell and undifferentiated sarcoma (8.9%), and Ewing sarcoma (4.1%). Compared with older children, infants had a higher risk of TRM (4.8% vs. 1.5%; HR (hazard ratio) 4.03; p = 0.003), inferior 1-year (63.7% vs. 81.5%; p < 0.001) and 5-year OS (56.9% vs. 62.0%; p < 0.001), and a lower but non-significant 5-year CIR (26.3% vs. 38.4%; p = 0.19). After adjustment for tumor subtype and metastatic status, infancy remained independently associated with poorer OS (adjusted HR 1.61, 95% confidence interval [CI] 1.13-2.31; p = 0.009).

Despite no increased risk of relapse, infants with bone and soft tissue neoplasms have significantly poorer survival than older children, primarily due to a substantially higher risk of TRM.