1661P Prognostic Role of Regional Lymph Node Metastases in Soft Tissue Sarcomas

The nodal involvement status in sarcoma patients (pts) is traditionally considered to correlate with similar prognosis as the distant metastases. However, the data on radical treatment in sarcoma pts with resectable nodal metastases is limited. The aim of this study was to assess the outcomes of sarcoma pts treated with sentinel lymph node biopsy (SLNB) and therapeutic lymph node dissection (TLND) due to regional lymph node metastases. In this retrospective study, we enrolled 64 subsequent pts treated in our institution between 1996 and 2019, who underwent SLNB and/or TLND. TLND was performed due to palpable nodal metastases or after positive SLNB. The clinicopathological data were retrieved from electronic health records. The overall survival (OS) was calculated from the radical resection of involved LN to death. Kaplan-Meier estimator and Cox's proportional hazard model were used. 27 females and 37 males were treated including 24 pts with epithelioid sarcoma (ES), 21 - clear cell sarcoma (CCS), 12 - synovial sarcoma (SaSy), and 7 with rhabdomyosarcoma (RMS). The median age was 35 (IQR: 25-46). The median follow-up period was 66 months (95%CI: 60-118). SLNB was performed in 33 cases and positive in 12 (6 ES, 3 CCS, 2 RMS, 1 SaSy). All but one patients with positive SLNB and all pts with resectable clinically detected nodal metastases underwent TLND (positive in 37 cases). Overall no nodal involvement was found in 21 cases (SLN negative), micrometastatic nodal involvement (positive SLNB and negative TLND) in 9 cases and positive TLND - in 34 cases. There were no significant differences in OS between cases with non and with micrometastatic nodal involvement and for those pts OS was 70 months (95%CI: 54-NA). In the group of pts with LN metastases confirmed in TLND the median OS was 18 months (95%CI: 17-48) only. The difference between these two groups was significant with a hazard ratio of 4.6 (95%CI: 2.1-9.7, p < 0.001). Presence of macroscopic metastases in regional lymph nodes is related to poor prognosis in sarcoma patients. Early detection of LN metastases by SLNB in sarcoma subtypes know for frequent LN involvement maybe related to improved treatment efficacy and survival of those patients.