Abstract 2394: Significance of regional lymph node dissection in patients with clear cell sarcoma and epithelioid sarcoma

Abstract

Abstract Objective Clear cell sarcoma (CCS) and epithelioid sarcoma (ES) are common as soft-tissue sarcoma subtypes causing lymph node metastasis (LNM), but the role of regional lymph node dissection is still unclear especially in these patients without imaging evidence of LNM. Here we retrospectively investigated the significance of lymph node dissection for patients with CCS and ES. Methods Forty-one patients (CCS: 13, ES: 28) with no distant metastasis other than in the regional lymph nodes were enrolled in this study. Of these 41 patients, those without LNM on imaging findings were categorized into two groups: "with dissection (WD)" group and "no dissection (ND)" group, respectively. Overall survival (OS), lymph node metastatic-free survival (LNMFS), progression-free survival (PFS), and post-operative LNM rate were compared between two groups. Results There were 26 patients who had undergone regional lymph node dissection and 15 patients who had not undergone regional lymph node dissection (ND group). Histopathological examination revealed metastasis to the lymph nodes in 9 of the 26 patients (38.5%). 9 patients were suspected of having LNM based on preoperative imaging findings such as CT or FDG PET/CT. Among the remaining 17 patients (WD group) in whom LNM was not suspected based on preoperative imaging findings, 6 patients (35.3%) had LNM. OS (p=0.03), LNMFS (p<0.01), and PFS (p<0.01) were all significantly better in the WD group. The postoperative LNM rate was significantly lower in the WD group than in the ND group (p=0.03), and there were no significant differences in OS, LNMFS, or PFS between the CCS and ES groups in terms of histological type. Discussion Even in cases where LNM was not suspected on preoperative imaging, LNM was present in more than 30% of cases. The possibility of regional LNM should be borne in mind in soft-tissue sarcomas, which frequently present with LNM, regardless of imaging findings. We also suggested that simultaneous dissection of the regional lymph nodes at the time of resection of the primary tumor improves the prognosis. Although ES and CCS are ultra-rare sarcomas, further validation with the accumulation of case series is desirable. Citation Format: Toshiyuki Takemori, Eisuke Kobayashi, Shintaro Iwata, Koichi Ogura, Shuhei Osaki, Suguru Fukushima, Akira Kawai. Significance of regional lymph node dissection in patients with clear cell sarcoma and epithelioid sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2394.