Implications of Lymph Node Evaluation in the Management of Resectable Soft Tissue Sarcoma.

Abstract

The rate of lymph node (LN) metastasis is rare in soft tissue sarcoma, but there are histologic subtypes that metastasize via the lymphatics. The prognostic value of LN evaluation in these high-risk histologies is unknown. Resected soft-tissue sarcoma patients with clear cell sarcoma, epithelioid sarcoma, rhabdomyosarcoma, or angiosarcoma (n=2993) were identified in the National Cancer Data Base (2004-2013). Cox regression evaluated the association of omission of LN assessment (NX) and overall survival (OS). Subjects who underwent surgical resection with or without regional LN evaluation were matched (1:1) by propensity scores based on the likelihood of NX or survival hazard on Cox modeling. OS was compared by Kaplan-Meier estimates. A total of 637 (21.3%) underwent LN evaluation and 176 (5.9%) were found to have nodal metastasis. Omission of nodal evaluation was significantly associated with risk of death (reference: N0; N+: hazard ratio [HR] 1.46, 95% confidence interval [CI] 1.11-1.91; NX: OR 1.18, 95% CI 1.00-1.40). After propensity score matching, there was a significant difference in median OS following pathologic identification of nodal disease for epithelioid sarcoma (N0: not reached vs. N+: 55.9months vs. NX: not reached, p=0.001) and clear cell sarcoma (N0: not reached vs. N+: 20.0months vs. NX: 95.0months, p<0.001). These data support more standardized approaches to regional lymph node examination for patients with epithelioid and possibly clear cell sarcoma and provide compelling evidence that nodal evaluation can be considered a quality measure in the delivery of cancer care for certain sarcoma subtypes.