Introduction
Non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) are rare childhood
malignancies that account for 3-7% of pediatric cancers
annually.1,2 Comprising over 50 histological subtypes,
NRSTS have a wide variety of clinical presentations and treatment
pathways. Across all histological subtypes, overall survival (OS) is
associated with tumor grade, tumor size, evidence of metastasis, and
extent of surgical resection.3 Studying outcomes for
individual subtypes is challenging due to low incidence. As a result,
pediatric providers rely on results from adult literature as well as
pediatric studies that aggregate subtypes by similar clinical or genetic
features.3-5
One common grouping of NRSTS is by propensity for early lymph node
metastasis. Most NRSTS rarely metastasize to lymph
nodes4,6, but higher risk NRSTS subtypes historically
included clear cell sarcoma of soft tissue (CCS), epithelioid sarcoma,
and synovial sarcoma.7 Over the past two decades,
large database studies in adults and single-center studies in children
have corroborated lymph node metastases are prevalent in up to 30% of
patients with CCS and epithelioid sarcoma.4,6,8-10Conversely, synovial sarcoma in adults is now understood to have an
incidence of lymph node metastasis as low as 4.2%6,9,
but this association has not been well-studied in children.
Understanding the incidence of lymph node involvement in children with
NRSTS tumors is important, as both the adult and pediatric literature
support an association between lymph node metastasis and inferior OS
across all NRSTS subtypes.3,6,9,11 Additionally,
patients identified with lymph node metastasis can receive targeted
radiation or completion lymphadenectomy to reduce tumor
recurrence.12 However, physicians must weigh suspicion
for lymphatic involvement against the risks associated with sampling
procedures, including wound infection and
lymphedema.13 Current recommendations include routine
lymph node pathologic evaluation in children with CCS and epithelioid
sarcoma. However, further data are needed to understand the impact of
lymph node sampling on survival in pediatric patients.
We sought to clarify trends of lymph node metastasis in pediatric
patients with CCS, epithelioid, and synovial sarcoma from a nationwide
database. We also explored lymph node sampling practices for these NRSTS
subtypes over the past decade. Finally, we examined the association
between lymph node sampling, lymph node metastasis, and overall survival
in this population.