Incidence and Survival Outcomes of Patients with High-Grade Appendicular Bone Sarcoma and Isolated Regional Lymph Node Metastasis: A National Cohort Database Study

Background While distant metastases in primary bone sarcomas have been extensively studied, the impact of isolated regional lymph node (LN) metastasis on survival remains unknown. In patients with primary bone sarcomas, we sought to assess the prevalence of isolated regional LN metastasis and the survival of this population. Methods A total of 6651 patients with histologically-confirmed high-grade osteosarcoma, Ewing sarcoma, or chondrosarcoma were retrieved from the SEER database. We defined four subgroups for our analysis: localized disease (N0 M0), isolated regional LN metastasis (N1 M0), isolated distant metastasis (N0 M1), and combined regional LN and distant metastasis (N1 M1). Disease-specific survival (DSS) was assessed using the Kaplan-Meier method. Results Prevalence of isolated regional LN metastasis (N1 M0) was highest in Ewing sarcoma (27/1097; 3.3%), followed by chondrosarcoma (18/1702; 1.4%) and osteosarcoma (26/3740; 0.9%). In all three histologies, patients with isolated regional LN metastasis had a worse 2-year, 5-year, and 10-year DSS than those with localized disease. Chondrosarcoma patients with isolated regional LN (N1 M0) metastasis had a significantly higher DSS in comparison to those with only distant metastasis (N0 M1) at the 5- and 10-year marks; for osteosarcoma and Ewing sarcoma, only a pattern towards higher survival was seen. Risk factors for presenting isolated regional LN metastasis included tumor location in lower-limb (OR=2.01) or pelvis (OR=2.49), diagnosis of Ewing sarcoma (OR=2.98), and tumor >10 cm (OR=1.96). Conclusions Isolated regional LN metastases in primary bone sarcomas is an infrequent presentation associated with worse survival than localized disease. Level of Evidence III